The Odonata of Canada and Alaska: Volume Two, Part III: The Anisoptera–Four Families 9781442654198

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Scholarly Reprint Series The Scholarly Reprint Series has been established to bring back into print valuable titles from the University of Toronto Press backlist for which a small but continuing demand is known to exist. Special techniques (including some developed by the University of Toronto Press Printing Department) have made it possible to reissue these works in uniform case bindings in runs as short as 50 copies. The cost is not low, but prices are far below what would have to be charged for such short-run reprints by normal methods. The Scholarly Reprint Series has proved a valuable help to scholars and librarians, particularly those building new collections. We invite nominations of titles for reissue in this form, and look forward to the day when, with this series and other technological developments, the label 'out of print' will virtually disappear from our backlist.

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The O D O N AT A of Canada and Alaska By

E D M U N D M. W A L K E R Professor Emeritus of Zoology, University of Toronto Honorary Curator of Zoology, Royal Ontario Museum

VOLUME TWO PART mi THE ANISOPTERA—FOUR FAMILIES

UNIVERSITY OF TORONTO PRESS:1958

Copyright ©, Canada, 1958 University of Toronto Press SCHOLARLY REPRINT SERIES ISBN 0-8020-7076-0 LC A 54-4344 rev. Printed in Canada

FOREWORD WHEN Dr. Walker retired from the staff of the University of Toronto in 1948, he was appointed Honorary Curator of Entomology in the Royal Ontario Museum. Freed from such time-consuming duties as lecturing and administrative activities, he was able to devote more of his energies to the subject of the distribution and taxonomy of the Odonata of Canada—a subject most dear to his heart. There was no doubt in our minds that the wealth of information on this subject possessed by Dr. Walker, when transposed to the printed word, would make a very fine contribution to the study of the fauna of Canada; so he commenced at once the preparation of the manuscript. Within a short time it became obvious that it would be quite impossible to publish all of the information in one volume, and so, after due deliberation, it was agreed that the complete work would be published in two volumes, one being devoted to the damselflies (Zygoptera) and the other to the dragonflies (Anisoptera). It was with a feeling of pride that the Royal Ontario Museum published, through the offices of the University of Toronto Press, Volume I, in 1953. Having completed Volume I, Dr. Walker immediately started to work on Volume II. Once again, it was found that there was far too much material for inclusion in a single volume, unless it were to be an exceedingly large volume, costly to produce and expensive to buy. This factor of size, together with the author's realistic approach to the relation between his age and the work to be done, led to the agreement that Volume II should be divided into two separate volumes. A consideration of the families Aeshnidae, Petaluridae, Gomphidae, and Cordulegastridae would constitute Volume II and that of the Macromiidae, Corduliidae, and Libellulidae would constitute Volume III. We are delighted to present the second volume of the series. The author has been an ardent student of the Odonata for over fifty years. Unlike some taxonomists who deal only with dead specimens, Dr. Walker has studied the living insects and, in so doing, he has added much to the knowledge of the species concerned, as well as giving a feeling of the out-ofdoors to his book. Writing of Aeshna mutata: "The flight appeared to be more leisurely than that of most Aeshnas. Soon another appeared on the scene and by a lucky stroke we netted one of them." When we add to this the author's artistic abilities—few authors can equal the fineness of his pen-and-ink drawings—we have indeed a rare combination of talents, the synthesis of which can only result in a book of excellent quality. It is my most sincere hope that, in the not too distant future, the final volume of the series will appear in published form, thus completing a lifetime's work by a brilliant Canadian scholar. F. A. URQUHART

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PREFACE SOME changes in terminology have been introduced into Volume II, which require a word of explanation. In Volume I the system followed was frankly based on current usage rather than on comparative morphology, as we would have preferred. This was done for two reasons: firstly, because morphdlogists were not agreed in their interpretation of many of the parts most frequently mentioned and, secondly, because purely descriptive terms are preferred, we believe, by most taxonomists, who are not concerned with morphological interpretations. It happened, however, that during the preparation of Volume I a group of British odonatists were striving to attain uniformity in the terminology used in describing odonate structures, particularly those of the larvae or nymphs, and at about the same time, there appeared Snodgrass' fine paper on the external structure of the larval dragonfly (Snodgrass, 1954) in which the terminology is strictly morphological. As we are thoroughly in sympathy with this movement, we are making the necessary changes, which fortunately are not very numerous. We regret that in Volume I no reference was made to the Tillyard-Fraser system of wing venation, which is largely based on the study of the fossil record. We have introduced it into Volume II because we believe it rests on a sound foundation. In any case it is too important a contribution to be ignored. To the acknowledgments made in Volume I we would add our thanks for valuable new material to G. H. Beatty, G. H. Bick, Carl Cook, T. H. Donnelly, R. H. Gibbs, Paul Hahn, Adrien Robert, and Minter Westfall; to Miss E. Chalmers for her careful editing of the typescript and proofs; and we would also like to express our appreciation of the excellent work of Miss Mildred Easto as Secretary and Miss Eileen McClure as Librarian to the Division of Zoology and Palaeontology of the Royal Ontario Museum. Finally, I wish to give special thanks to my sister-in-law, Miss Marjory A. Ford, for her valuable assistance in detecting certain types of error which are liable to be overlooked. As to the illustrations: plates 1, 2, 8, 10 (figures 2 and 3), and 11 (figures I and 2) are from photographs by Mr. Wm. Carrick; all others are by the author. E.M.W.

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ABBREVIATIONS GENERAL abd.—abdomen, abdominal ant.—anterior anx.—antenodals app.—appendage excl—excluding exuv.—exuvia, exuviae f. w.—fore wing h. f.—hind femur hd.—head

h. w.—hind wing inf.—inferior lat.—lateral pnx.—postnodals pt—pterostigma, -ta seg.—segment spt—supratriangle w.—width PROVINCES OF CANADA

Alta.-Alberta B.C.—British Columbia Labr.—Newfoundland (Labrador) Man.—Manitoba Nfld.—Newfoundland (Island) N.B.—New Brunswick

N.S.-Nova Scotia Ont—Ontario P.E.I.—Prince Edward Island Que.—Quebec Sask.—Saskatchewan

TERRITORIES OF CANADA N.W.T.-North-West Territories

Y.T.-Yukon Territory

viii

CONTENTS FOBEWOBD BY DB. F. A. UBQUHABT

v

PREFACE

vii

ABBREVIATIONS

viii

PART III. THE ANISOPTERA OF CANADA AND ALASKA General Characteristics of Anisoptera Key to the Families of Anisoptera FAMILY AESHNIDAE SELYS

Key to the Genera of Aeshnidae Genus Boyeria McLachlan Key to the Species Boyeria Boyeria vinosa (Say) Boyeria grafiana Williamson Genus Gomphaeschna Selys Gompnaeschna furdUata (Say) Genus Basiaeschna Selys Basiaeschna Janata (Say) Genus Basiaeschna Selys Basiaeschna pentacantha (Rambur) Genus Epiaeschna Hagen Epiaeschna keros (Fabricius) Genus Aeshna Fabricius Key to the Species of Aeshna Aeshna eremita Scudder Aeshna interrupta Walker The Subspecies of Aeshna interrupta Aeshna interrupta interrupta Walker Aeshna interrupta lineata Aeshna interrupta interna Walker Aeshna canadensis Walker Aeshna v&rticalis Hagen Aeshna clepsydra Say Aeshna tuberculifera Walker Aeshna juncea Linn£ Aeshna subarctica Walker Aeshna sitchensis Hagen Aeshna septentrionalis Burmeister Aeshna palmata Hagen Aeshna umbrosa Walker ix

1 3 12 14

19 21 22 23 27 29 33 35 35 39 41 43 44 47 49 57 60 62 63 65 67 68 73 77 79 83 87 90 95 99 102

x

CONTENTS

Aeshna umbrosa umbrosa Walker Aeshna umbrosa occidentalis Walker Aeshna constricta Say Aeshna calif arnica Calvert Aeshna multicolor Hagen Aeshna mutata Hagen Genus Anax Leach Anax junius Drury FAMILY PETALURIDAE NEEDHAM

Key to the Genera of Petaluridae Genus Tanypteryx Kennedy Tanypteryx hageni (Selys)

FAMILY GOMPHIDAE RAMBUR

Key to the Genera of Gomphidae Subfamily Hageniinae Genus Hagenius Selys Hagenius brevistylus Selys Subfamily Gomphinae Genus Ophiogomphus Selys Key to the Species of Ophiogomphus Ophiogomphus severus Hagen Ophiogomphus severus severus Hagen Ophiogomphus severus montanus (Selys) Ophiogomphus colubrinus Selys Ophiogomphus aspersus Morse Ophiogomphus carolus Needham Ophiogomphus mainensis Packard Ophiogomphus occidentis Hagen Ophiogomphus rupinsulensis (Walsh) Ophiogomphus anomalus Harvey Genus Lanthus Needham Key to the Species of Lanthus Lanthus albistylus (Hagen) Lanthus parvulus (Selys) Genus Octogomphus Selys Octogomphus specularis (Hagen) Genus Gomphus Leach The Subgenera of Gomphus Semi-artificial Key to the Species of Gomphus Key to the Species of Gomphus Subgenus Gomphus Leach Gomphus lividus Selys Gomphus graslinellus Walsh Gomphus quadricolor Walsh

103 107 109 113 117 121 125 126 131

133 134 134 135

143 146 146 146 149 149 150 154 154 157 158 161 162 165 167 170 173 174 175 177 179 181 182 185 189 193 197 207 207 211 215

CONTENTS

Gomphus exilis Selys Gomphus spicatus Hagen Gomphus descriptus Banks Gomphus borealis Needham Subgenus Arigomphus Needham Gomphus villosipes Selys Gomphus furcifer Hagen Gomphus cornutus Tough Subgenus Gomphurus Needham Gomphus fraternus (Say) Gomphus fraternus fraternus (Say) Gomphus fraternus manitobanus subsp. n. Gomphus externus Hagen Gomphus ventricosus Walsh Gomphus vastus Walsh Subgenus Hylogomphus Needham Gomphus brevis Hagen Gomphus viridifrons Hine Subgenus Stylurus Needham Gomphus amnicola Walsh Gomphus intricatus Hagen Gomphus scudderi Selys Gomphus notatus Rambur Gomphus plagiatus Selys Gomphus spiniceps (Walsh) Gomphus olivaceus Selys Genus Dromogomphus Selys Dromogomphus spinosus Selys FAMILY CORDULEGASTRIDAE CALVERT

Genus Cordulegaster Leach Key to the Species of Cordulegaster Cordulegaster maculatus Selys Cordulegaster diastatops Cordulegaster dorsalis Hagen Cordulegaster obliquus (Say)

XI

222 218 225 227 231 231 235 238 242 242 243 247 249 251 254 257 257 261 262 262 265 267 271 274 278 282 285 285 289

290 293 294 298 301 305

BIBLIOGRAPHY

309

INDEX

315

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PART III

THE ANISOPTERA OF CANADA AND A L A S K A

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THE A N I S O P T E R A OF C A N A D A AND A L A S K A THE Anisoptera are the "dragonflies proper" as distinct from the Zygoptera or damselflies, and constitute by far the greater of the two suborders of Odonata. They are, on the whole, larger and more robust than the damselflies. The head is not hammer-shaped as in the latter group but compact with less prominent eyes which usually meet for a variable distance between the vertex and the occiput, or, if separated, by a distance less than the depth of one of the eyes. The dissimilarity between the fore and hind wings, from which the name Anisoptera is derived (Greek &viaos9 unequal; wrepbv, a wing), is much greater than in the Zygoptera, the hind wings being much broader near the base than the fore wings. Neither are ever petiolate and the hind wings are always more or less widened through the expansion of the anal area. The characteristic position of the wings, both during flight and when at rest, is complete lateral extension, although they are held in the vertical plane for a short time after the imago first emerges from the nymphal cuticle. The differences in the form of the wings in the two suborders are correlated with differences in flight. The wings of Zygoptera are like paddles and their flight is accomplished by a sculling movement, devoid of the soaring and planing such as we see, to some extent at least, in all of the Anisoptera. GENERAL CHARACTERISTICS OF ANISOPTERA

ADULTS Limiting our treatment to external features, we may consider these under the headings of the three body regions. Head The head is always more compact than in the Zygoptera, but the compound eyes vary in size from those of the Gomphidae and Petaluridae, which are comparatively small and widely separated, to those of the Aeshnidae, Macromiidae, Corduliidae and Libellulidae, in which they are nearly hemispherical, meeting in the mid-dorsal line for an appreciable distance (the eye-seam), and thus dividing the epicranium into an anterior and posterior area, the anterior area consisting of the frons and vertex, the posterior area of the occiput or, as it has sometimes been termed, the occipital triangle. In the Cordulegastridae* the eyes are intermediate between the usual types since they either meet at a point or are barely separated. The antennae are always setaceous and inconspicuous, and are typically seven-segmented. The first two segments, termed scape and pedicel respectively, are always clearly distinguishable and comparatively thick, but the remaining segments, * Usually but less correctly Cordulegasteridae, see p. 289. 3

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THE ODONATA OF CANADA AND ALASKA

called the whip or flagellum, are slender and taper to a fine hair-like extremity. In the Gomphidae the flagellum is not divisible into segments, but in other families it is generally quite distinctly divided. For convenience the anterior surface of the frons is called the antefrons, the dorsal surface the postfrons. The labium offers some important taxonomic characters. In the more primitive groups, including the first four families, the labial palpi are relatively small and do not meet along the middle line as they do in the Libelluloidea (Macromiidae, Corduliidae and Libellulidae). The movable hook, however, is relatively well developed and the end-hook is often a long and slender spine, which is turned dorsad, probably serving to impale the prey when the insect is feeding. Other smaller spines may also be present. The middle lobe in these more primitive forms is exposed to view and is either minutely cleft or bilobed, as in the Petaluridae and Cordulegastridae, and to a slight extent in the Aeshnidae, or entire as in the Gomphidae. In the Libelluloidea the labial palpi are much broader, their distal margins meeting along the middle line and concealing the median lobe, which is very small and without any cleft. This is a character by which the two main divisions of the suborder may be easily separated. Other characters will be described under the headings of families. Thorax In all of the Anisoptera the interpleural suture (hitherto referred to as the first lateral suture) is vestigial or absent, the mesothorax and metathorax being completely united. The sutures that we have hitherto termed the humeral and the second lateral sutures are morphologically the mesopleura! and metapleural sutures respectively and will henceforth be so designated. Except for the colour patterns, characters of the thorax itself have not often been found very useful in the taxonomy of the Anisoptera, but the thoracic appendages, the legs and wings, are extremely important, particularly the wings, since it is upon the venation that the classification is chiefly based. Legs The legs of Anisoptera, like those of the Zygoptera, are used almost entirely for perching and we find parallel adaptations in the two groups. Many dragonflies perch on the vertical bark of trees, on the oblique support of a bending grass stem, on a sloping rock or the flat ground. In all species the front legs are shortest, the middle legs are generally a little longer, and the hind legs are longest. But the relative length of the legs as compared with the body length varies considerably, and the comparative lengths of the femur and tibia also vary. Usually they are nearly the same, but in the Gomphidae, which habitually perch on horizontal surfaces, the middle and hind tibiae are considerably shorter than the corresponding femora. As a rule the legs bear an armature of spines and may also be thinly

GENERAL CHARACTERISTICS OF ANISOPTERA

5

clothed with hairs. The arrangement and size of the femoral spines are very varied. The dorsal surface is usually nearly free from spines, and any that are present are extremely short. In the Gomphidae these spines are most abundant ventrally, but may be scattered over the lateral surfaces as well, sometimes extending even to the dorsal surface. Ventrally the spines tend to become arranged along the sides of a clear distal area terminating at the femoro-tibial articulation, where the spines are generally largest. There is occasionally, however, a series of larger spines in addition to the usual short ones, as in Dromogomphus. In the Aeshnidae and Cordulegastridae the ventral surface of the femora is bounded by a pair of ridges, on each side of which the spines are arranged in a single row. In the Libelluloidea also there are two series of ventral femoral spines, but they are composed of numerous crowded spines, to which may be added one or more rows of hairs or stiffish bristles. In all our Anisoptera the fore tibiae bear on the mesal side, toward the distal end, a close-set series of short bristles, known as the comb. Another structure found only in certain groups of Anisoptera is that of tibial keels. In our native fauna these are well developed only in the Macromiidae and the Corduliidae, but occur as vestiges in the Gomphidae and Cordulegastridae. They are thin, translucent keel-like ridges on the flexor side of the tibiae. They extend from the distal end of the tibia a variable distance towards the proximal end. They are often absent or vestigial on the middle tibiae when present on the other two pairs. Further reference will be made to them in dealing with the groups in which they are present.

Wings

The classification of the Anisoptera into families and subfamilies is based largely upon venational characters and these have been freely used in the keys that follow. As stated in the Preface to Volume II, we have introduced the system of Tillyard and Fraser, feeling that both their system and that of Needham should be familiar to students of the Odonata. The system outlined by Tillyard in 1928 and later elaborated by Tillyard and Fraser (1938-40) was based primarily on Tillyard's long study of the fossil record of the Odonata and their precursors, combined with extensive researches on the recent forms. In these studies emphasis is laid on the importance in the earliest winged insects of alternating convex and concave veins as a means of identifyng these veins. This is especially true of the Palaeoptera, that group of insect orders which are unable to fold their wings over the back of the abdomen in the form of a roof. The only living representatives of the Palaeoptera are the Odonata and the Ephemeroptera, all other recent orders belonging to the Neoptera, in which the folding of the wings over the back of the abdomen was already established in the ancestral orders of the Upper Carboniferous. In the primitive type of palaeopterous wing each vein arising from the base of the wing, except the anal vein, is divided into an anterior convex

6

THE ODONATA OF CANADA AND ALASKA

and a posterior concave branch. The anal vein has always been different from the other veins and has never given evidence of a division into convex and concave branches. The costa (C) and subcosta (Sc) are actually the convex and concave branches of the most anterior vein of the wing and their ideal notation would be CA (anterior costa) and CP (posterior costa), but the older notation is still followed as it has been used in all the insect Orders. The radius (R) likewise divides into convex and concave branches, the convex branch being the vein commonly known as R1} the concave branch as the radial sector (Rs), which divides into R2, RS, R4 and R5. RA would thus be the ideal notation for RI and RP for Rs. In all these cases, however, the old notation has been retained for convenience. The median vein was also originally divided into convex and concave branches, but the concave branch, originally present in certain very early precursors of the Odonata, has long ago disappeared and only the convex or anterior branch (MA) remains. On the other hand, the cubitus (Cu) has left only the concave or posterior branch (CuP), which is the first branch (Cul) of the ComstockNeedham system, the second branch (Cu2) being the anterior anal of the new system. Another factor in the development of Tillyard's new venational system was his conviction that the "larval wing tracheation, while corresponding in general with the imaginal cannot be relied upon to determine the veins in every detail" (Tillyard, 1928). He had been puzzled over the fact that the vein generally known as Rs, although apparently identical in the Anisoptera and Zygoptera, had different tracheal supplies. Further investigation showed that there were four different sources of supply, a fact which suggested that it was the tracheation that was variable, not the venation. Eventually, through a study of primitive Zygoptera from the Upper and Lower Permian, it was apparent that the supposed Rs was not a true vein but an interpolated or intercalary vein with a Y-vein connection to the two veins in front and behind it. (Intercalary veins are indicated in the notation with a capital I before the designation of the vein in front of it. This vein, therefore, being preceded by R3, becomes I R3.) The radial sector according to this interpretation is the anterior sector of the arculus. The radial and median supplements remain as before. In all the Anisoptera there is a series of cross-veins in the costal space known as the antenodal cross-veins or simply antenodals. In the subcostal space, immediately behind, there is another series of cross-veins, which may or may not be in alignment with those of the costal space. We distinguish these two series of antenodals as the first and second series respectively. In the more generalized wings of the Aeshnoidea and Cordulegastroidea the two series are either not in alignment at all or only partly so, whereas in the Libelluloidea there is a definite alignment, although one or two of the second series at the distal end may be wanting. In all but the Libellulidae there are two antenodals in each wing that are thicker

GENERAL CHARACTERISTICS OF ANISOPTERA

7

than the others and extend across the costal and subcostal spaces. One of these stout veins is always the first of the series and the other is not far from it, usually about the fifth or seventh. These thickened veins are very ancient structures and, according to Fraser (1940), are homologous with the two antenodals that are present in all of our Zygoptera except the Agriidae. They are hence known as the primary antenodals. The presence of only two antenodals in the Lestidae and Coenagriidae (and other families not represented in our fauna) has been shown by Tillyard and Fraser (1938-40) to be a primitive feature, first seen in the fossil Protozygoptera. Their presence in the more primitive Anisoptera of recent times is believed by Fraser to be part of the evidence for the evolution of the Anisoptera from zygopterous ancestors. The primary antenodals of the two series are always in alignment, but when they are well developed there is little alignment between the secondary antenodals. On the other hand, when the primary antenodals are indistinguishable from the secondaries, there is complete or almost complete alignment. A transitional condition is met with in the more primitive groups of Libelluloidea (Macromiidae, Corduliidae) in which the first two antenodals of the two series are slightly thicker than the others and are probably the primary antenodals. Pterostigmata are always present in the Anisoptera. Possibly the most archaic form is found in the family Petaluridae in which they are extremely long, surmounting ten cells or more, but not exceeding the ordinary width of the costal space. The more specialized pterostigmata tend to become shorter and wider and more or less elliptical. The presence of an oblique brace-vein, just behind the pterostigma and in alignment with its proximal margin is a feature distinctive of most of the more primitive families, but is absent in nearly all the Libelluloidea. The region of the arculus and triangles and other associated structures near the base of the wing affords some of the most important venational features. The sectors of the arculus, which are formed, as already stated, by the basal parts of Rs and MA, vary as to the position at which they leave the arculus, and as to whether they are separate from one another or united as they leave it. Generally speaking, separate sectors represent a more primitive condition than those which are united. Well-separated sectors are found, for example, in the primitive families Petaluridae and Cordulegastridae, whereas in many of the libellulid genera they are united for some distance. The triangle and supratriangle, arising as the two divisions of an original quadrilateral space, the discoidal cell, were both imperfectly triangular during the early stages of their evolution; but, although traces of these earlier forms are sometimes seen in recent Odonata, it is the secondary elongation of the triangle and its positive relation to the arculus that are of systematic importance, and also the size, form and position of the subtriangle. In their more primitive form, in various families of Anisoptera, the

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THE ODONATA OF CANADA AND ALASKA

triangles are short, the transverse or proximal side long, being about as long as the costal or anterior side. Thus in the fore wings of the Gomphidae the triangles are often scarcely elongated, if at all, and in the hind wings they are slightly lengthened in the long axis of the wing. In the Aeshnidae we again find the triangles similar in the two pairs of wings and elongated as in the Cordulegastridae but to a greater extent. Thus the general trend in these families is towards elongation of the triangles in the long axis of the wing. In all these families the triangles are distal to the arculus and this is their primitive position. In the Libelluloidea there is a distinctly different trend in the elongation of the triangles and the development of the subtriangle. The triangle of the fore wing is elongated transversely and lies decidedly distad of the arculus. Associated with the narrowing of the triangle is an expansion of the subtriangle, which is generally three-celled and more or less four-sided. It no longer appears to occupy the distal end of the cubito-anal space but to lie behind the anal vein. This is an appearance only, due to the shifting in position of the proximal and anterior sides of the triangle. In the hind wing the triangle is elongated in the long axis of the wing and its position is shifted towards the base, so that its proximal side is in alignment with the arculus. The second cubito-anal cross-vein is unstable and tends to drop out, so that there is usually no subtriangle, or at most a small and unimportant one. With the widening of the hind wing at base the anal loop acquires greater significance as a support for this part of the wing. It remains short and broad in the Macromiidae, but in the Corduliidae* it is long and curved and consists of two rows of cells bisected by a supplement or midrib and is usually widened a little at the end by the addition of a few cells. In the Libellulidae the anal loop is similar to that of the Corduliidae, but the terminal part is better defined and has acquired a form suggestive of a human foot with toe and heel, and the midrib is bent backward and continues to the tip of the toe. In depauperate genera, such as Nannothemis, the anal loop may become reduced and no longer present this foot-like outline. Supplements Besides the midrib of the anal loop there are two supplements that are of some value in the classification of anisopteran genera, if not of families. These are the radial and median supplements or planates. The radial supplement (Rspl) is between IR 3 and R4+5,t usually close to the former from which it is separated usually by one or two rows of cells, but sometimes, as in certain aeshnid genera, it swings backwards and then forwards again, leaving a space in which there may be four or five rows of cells at the *In certain exotic groups generally referred to Corduliidae the anal loop is not as here described. tRs and Ms according to the Comstock-Needham System.

GENERAL CHARACTERISTICS OF ANISOPTERA

9

widest part. The median supplement bears a similar relation to MA and may run close to it, separated by a single row of cells, or may curve away from it to a distance of several rows. Both supplements may have all the appearance of a genuine longitudinal vein, except that they lack a definite beginning or ending. Even this may be present in intercalated veins. NYMPHS As stated in the Preface we are using a revised terminology in conformity with the efforts of those workers who are seeking uniformity and the recognition of terms based on the accepted views of comparative morphologists. The changes of terminology apply chiefly to the nymphs and particularly to highly specialized structures, such as the labium and the terminal appendages which comprise the anal pyramid, namely the cerci and its associated structures. Labium The primitive labium of insects consists of two median unpaired segments, separated by an articulation, on which the distal segment is movable upon the proximal segment. It bears the labial palpi and the terminal lobes, the median glossae and the lateral paraglossae. This two-segmented condition of the labial axis is retained in the larval labium of dragonflies, but there are two articulations, a basal one as well as the articulation between the two segments, and these two articulations, together with the elongation of both segments, render the arm extremely mobile and extensible. In the larval labium of dragonflies the proximal segment has long been known as the submentum and the distal segment as the mentum. But these terms are open to objection because the term mentum was first applied to the middle of three sclerites, present in the labium of various insect orders, such as the Coleoptera and Orthoptera. This middle segment is part of the proximal segment, separated from its distal end, or in some groups (Orthoptera) it is merely a resclerotization of the articular membrane proximal to the joint. This middle plate, then, is the mentum, the basal plate the submentum, the two together being divisions of the original proximal segment, which Snodgrass (1954) has termed the postmentum. In the larval labium of dragonflies (pi. 13) the proximal segment retains the primitive undivided form and is the postmentum. It is concealed in the resting position by the large median distal plate, which is the prementum. This is the structure that is commonly known as the mentum. There is in fact no true mentum present in the nymphal labium. The setae that are usually known as mental setae are thus the premental setae. The low distal shelf-like projection from the prementum, usually called the median lobe, is doubtless the ligula, a term applied to the paraglossae and glossae when they are fused to form a terminal lobe or lip, which may be either cleft or undivided. In Anisoptera with the flat type of labium it usually has a small median cleft, though it is undivided in the Gomphidae. The flattened setae

10

THE ODONATA OF CANADA AND ALASKA

borne by the distal margin of the ligula are termed by Corbet (1953) thv piliform setae. The ligula has entirely disappeared in the families with $ spoon-shaped labium, except the Cordulegastridae (postea). The labial palpi, long known as "lateral lobes," are a pair of two-jointec appendages, the proximal segment of which forms the main body of the palpus, or palpal lobe; the second segment, which is slender, curved, sharplj pointed, and much smaller, being the movable hook. In those families in which the labium is flat the narrow distal part of the palpal lobe is sometimes termed the blade. There are two main types of larval labium in the Anisoptera, with many variations. One of them is flattened and usually without palpal setae, the other is spoon-shaped and possesses these setae, as in most Zygoptera. In the first type, which is found in the Aeshnidae, Petaluridae and Gomphidae (pi. 13: 1, 2), the prementum is flat, without premental setae, the ligula (median lobe) usually broadly angulate with a median closed cleft (Aeshnidae, Petaluridae) or slightly arcuate, without a cleft (Gomphidae). The palpi are narrower than they are long and without palpal setae. The movable hook is long and overlaps its fellow extensively when the palpi are closed. This type of palpus is widest at the articulation of the movable hook, beyond which it is narrowed or parallel-sided, projecting mesad in the form of a lobe or endite, which usually bears dentations or very minute crenulations on the mesal margin. The distal extremity may be truncate (most Aeshnidae) or rounded, or it may be curved mesad, terminating in an end-hook. The second type of larval labium is found in the Cordulegastridae and Libelluloidea (pi. 13: 3, 4). The prementum is short and widens much more rapidly, and is dorsally concave like a spoon, with the anterior margin strongly produced but without a ligula except in the Cordulegastridae in which it is represented by a bifid prominence. A constant feature of this type of labium is the presence of premental setae, arranged in a single series on each side but variously subdivided into groups, including a main group of long setae and smaller groups of much shorter setae at the outer or inner ends of the main series. The labial palpi or palpal lobes are strongly concave within and are much broader than in the flat type, being triangular with a great widening of the distal margin, which is variously scalloped or incised. In the Cordulegastridae the incisions are deep and irregular, separating a series of sharp dentations, which are without setae. In the Libelluloidea the palpal margin is less deeply but more regularly cut, the incisions alternating with rounded or flattened crenations, each of which bears one or more spiniform setae. In many of the Libellulidae the crenations have disappeared and only the regularly arranged groups of setae remain. The movable hook is smaller than in the flat type of labium, being largest in the Cordulegastridae but very small in the other families, even becoming quite vestigial in the Libellulidae. A series of palpal setae is borne

GENERAL CHARACTERISTICS OF ANISOPTERA

11

along the outer margin of the palpus, terminating next to the movable hook. These setae have long been known as the lateral setae but are better termed the palpal setae. Terminal or Anal Appendages The three appendages surrounding the anus, known as the anal valves and forming the anal pyramid when closed, were briefly described in Volume I, Part I. The median dorsal appendage was termed in the text the superior appendage, the paired ventrolateral appendages the inferior appendages, and the small dorsolateral appendages were called the lateral appendages. Although their morphological designations were also given, these may be repeated here: the superior appendage is morphologically the epiproct and is the equivalent of the median caudal lamella of the Zygoptera; the two inferior appendages are the paraprocts; the lateral appendages are the cerci and are the segmental appendages of the eleventh segment, although they appear to belong to segment 10. Male anisopteran nymphs may be distinguished from female nymphs in the last instar by the developing genitalia which appear through the sternal cuticle of the second abdominal segment. They may also be recognized by a modification of the basal part of the epiproct which appears as a dorsal prominence or a pair of lateral processes and is due to the developing "inferior appendage" of the imago. It is known as the male projection and has also been termed, by Needham and Westfall, the basal tubercle and by Walker, when paired and lateral, as the ante-apical tubercles. SUPERFAMILIES

The Anisoptera have been variously divided into superfamilies. The following division is the most satisfactory one in our opinion. The second superramily, Cordulegastroidea, has been associated with both Aeshnoidea and Libelluloidea, but in view of its mixed characters we consider it deserving of independent rank. Aeshnoidea, Tillyard Adults. Distal edge of palpal lobes not meeting in the median line, the middle lobe exposed, cleft or entire; triangle of fore wing less than twice as far removed from the arculus as triangle of hind wing; triangles of both wings elongated in the long axis of the wing (except Petaluridae); two primary antenodal cross-veins, the other antenodals of the first series not in alignment with those of the second series, or only partly so; pterostigmata with a brace-vein; eyes variable in size and distance apart; ovipositor fully developed or absent, not extending beyond posterior end of abdomen. Nymph& Labium flat without premental setae; palpal lobes narrow with lateral and mesal edges subparallel, movable hook large, palpal setae almost always absent; ligula with or without a cleft. Three families: Aeshnidae, Petaluridae and Gomphidae.

12

THE ODONATA OF CANADA AND ALASKA

Cordulegastroidea, TiUyard and Eraser Adults. Distal edges of palpal lobes not meeting in the median line, middle lobe exposed, with an angular cleft; triangle of fore wing less than twice as far removed from the arculus as triangle of hind wing; with two primary antenodal cross-veins, the other antenodals of the first series not in alignment with those of the second series; pterostigmata without a bracevein; eyes meeting at a point or barely separated; ovipositor extending beyond posterior end of abdomen, without styli and with vestigial genital valves. Nymphs. Labium spoon-shaped, with premental setae; and movable hook smaller than in Aeshnoidea; Bgula a small cleft tooth-like process; palpal lobes broad and triangular with distal margin deeply and irregularly dentate, the dentations without setae; palpal setae present. One family in North America: Cordulegastridae. Libelluloidea TiUyard Adults. Distal margins of palpal lobes meeting in the median line, the small middle lobe concealed; triangles of fore wing at least twice as far from the arculus as triangles of hind wing; triangle of fore wing generally elongated transversely, that of hind wing longitudinally; primary antenodals (the first two) only slightly thickened or not at all; antenodals of the first series in alignment with those of the second series. Nymphs. Labium spoon-shaped, with premental setae; ligula absent; palpal lobes broad and triangular with distal margins smooth or evenly crenulate, the crenulations each bearing one or more setae or, in the absence of crenulations, the margin bearing evenly distributed setae, singly or in groups; movable hook small. Three families in North America: Macromiidae, Corduliidae and Libellulidae. KEY TO THE FAMILIES OF ANISOPTERA

ADULTS 1. Distal edges of palpal lobes not meeting in the median line, the median lobe exposed; triangles of fore wings less than twice as far from the arculus as triangles of hind wings; triangles of both wings generally elongated in the long axis of the wing; with two primary antenodal cross-veins, the other antenodals of the first series not in alignment with those of the second series, or only partly so 2 Distal edge of palpal lobes meeting in the median line, the small median lobe concealed; triangles of fore wings at least twice as far from the arculus as triangles of hind wings; triangles of fore wings generally

GENERAL CHARACTERISTICS OF ANISOPTERA

13

elongated transversely, those of hind wings longitudinally, without easily recognizable primary antenodal cross-veins, those of the first series in alignment with those of the second series 5 2. Eyes meeting in the mid-dorsal line for an appreciable distance; middle lobe of labium with a small median cleft; pt. with an oblique bracevein at the proximal end; inf. app. of male generally triangular, rarely bifurcate or truncate; ovipositor well developed with styligerous genital valves Aeshnidae Eyes separated or barely contiguous; inf. app. of male not triangular, usually quadrate or bifurcate; ovipositor usually small or vestigial but sometimes long 3 3. Eyes closely approximated or barely meeting; labium with a median cleft; pt. without a brace-vein; ovipositor extending beyond end of abdomen Cordulegastridae Eyes widely separated; pt. with a brace-vein; ovipositor never reaching end of abdomen 4 4. Median lobe of labium cleft; pt. longer than one-fourth of the distance from nodus to distal end of RI; subtriangle of fore wing generally divided into two or more cells; abdomen not enlarged distally; ovipositor complete, though small, with styligerous genital valves Petaluridae Median lobe of labium entire; pt. shorter than one-fourth the distance from nodus to distal end of RI; subtriangle of fore wing generally more or less enlarged distally (usually segs. 7-9); ovipositor reduced to a bifid vulvar lamina Gomphidae 5. Anal loop short and wide, without a midrib; triangle of hind wing remote from arculus; tarsal claws with nearly equal-sized hooks, the ventral one usually longer; abdomen without ventrolateral carinae; anterior hamules relatively well developed Macromiidae Anal loop long with two rows of cells separated by a midrib, usually somewhat widened near the posterior end; triangle of hind wing opposite the arculus; tarsal claws with unequal hooks, a long terminal and a short ventral one; abdomen with ventrolateral carinae on segs. 3 or 4 to 8 or 9; anterior hamules vestigial or absent 6 6. Posterolateral edges of eyes sinuous; "foot" of anal loop without a distinct "toe"; anal border of hind wings of male angulate; abd. seg. 2 of males with a pair of auricles and small anterior hamules; males with a tibial keel on fore and hind or all three pairs of legs; coloration usually metallic Corduliidae Posterolateral edges of eyes smoothly rounded; "foot" of anal loop nearly always with a distinct "toe"; anal border of hind wings rounded in both sexes; abd. seg. 2 of males without auricles; anterior hamules and tibial keels absent; coloration rarely metallic, never in our species Libettulidae

14

THE ODONATA OF CANADA AND ALASKA

NYMPHS 1. Prementum and palpal lobes flat or nearly so, with neither premental nor palpal setae 2 Prementum and palpal lobes together spoon-shaped, with both premental and palpal setae 4 2. Antennae 4-segmented; mesotarsi 2-segmented; ligula without a median cleft Gomphidae Antennae 6- or 7-segmented; mesotarsi 3-segmented; ligula with a median cleft 3 3. Prementum with sides subparallel in distal three-fifths, then abruptly narrowed near basal hinge, each palpal lobe with a stout dorsolateral spur at base of movable hook; epiproct not bifid at tip Petaluridae Prementum widest in distal half, much narrower in proximal half or more; no dorsolateral spur at base of movable hook; epiproct bifid at apex (not always distinct) Aeshnidae 4. Distal edges of each palpal lobe deeply cut into large irregular dentations, without associated groups of setae; ligula represented by a toothlike process, which is cleft Cordulegastridae Distal edge of each palpal lobe smooth or evenly crenulate, each crenulation bearing one or more setae; ligula not recognizable 5 5. Head with a prominent, suberect horn between the bases of the antennae; metasternum with a broad median tubercle; legs very long, the apex of each hind femur reaching to or beyond the hind margin of seg. 8 Macromiidae Head without a prominent median horn; metasternum without a median tubercle; legs shorter, the apex of each hind femur usually not reaching to the hind margin of seg. 8 6 6. Distal margins of palpal lobes with rounded crenations of which the highest are one-third to more than one-half as high as they are long 7 Distal margins of palpal lobes nearly straight or with very low crenations, many times longer than high Libellulidae 7. Lateral spines of seg. 8 as long as seg. 9 or longer Libellulidae, genus Pantala Lateral spines of seg. 8 shorter than seg. 9 or absent Corduliidae FAMILY AESHNIDAE SELYS

These are the large dragonflies with long spear-shaped bodies that are common and conspicuous in late summer when most of the other large Anisoptera have disappeared or declined in numbers. The head is large and nearly hemispherical, owing to the great development of the compound eyes, which meet for an appreciable distance between the vertex and occiput. As a result both of these head regions are much reduced, the vertex to a small mound-like structure, and the occiput to a

FAMILY AESHNIDAE

15

small triangular space, usually flat, at the rear of the head. The frons has a flat dorsum, sharply separated from the face. The ocelli are all visible from above, the median having about twice the diameter of a lateral ocellus. The ligula or median lobe of the labium has a very small cleft. The thorax is stout and the median carina is usually raised into an angular crest. The legs are moderately long, the femora little longer than the tibiae, which are without keels. They are used chiefly for perching in the vertical plane, aeshnids commonly "hanging up" from a twig or the bark of a tree, although some species, such as Anax junius and Aeshna constricta, hang up from low plants in open fields. The wings are usually nearly as long as the abdomen and are generally hyaline, sometimes tinted, but in our fauna almost devoid of spots, except small basal ones and of course the pterostigmata, which are of moderate length and supported by a brace-vein. The anal border of the hind wing is angulate in the males of all our genera, except Anax. Venational characters will be discussed later. The abdomen is subcylindrical with the carinae well developed on most of the segments. Thus there are well-marked mid-dorsal, lateral and transverse carinae, the lateral carinae being found on segments 3 to 9 and the transverse carinae on 2 to 8, dividing each segment into two sections. These sections are almost equal in length on segments 2 to 3, but on the remaining segments they are increasingly unequal, the anterior section becoming successively smaller in proportion to the posterior section until, on segment 8, it has nearly or quite disappeared. These seemingly unimportant details affect the basic type of abdominal colour-pattern, which can be traced through most of our genera and will be referred to later. In most Aeshnidae the abdomen appears inflated at the base, the enlargement including the first two segments. Segment 3 is constricted a little before the middle, particularly in the males, the abdomen enlarging again gradually, usually to about the fifth or sixth segment, and narrowing again thereafter. Sometimes there is little enlargement at base and little constriction following it, the abdomen tapering almost evenly to the end. Auricles or oreillets are present on the sides of segment 2 in the males in association with the accessory genitalia. The only special features of the male genitalia that we have used in the systematic treatment of the group are found in the anterior lamina and the anterior hamules, the posterior hamules being small and not easily seen (pis. 6, 7). The anterior lamina is divided by a median trough and usually bears on each side a spine or hornlike process, known as the spine of the anterior lamina (pi. 7: 1, 2). The anterior hamules are a pair of claspers, each consisting of two principal parts, the hamular process and the hamular fold. The hamular process (pi. 7: 1, 2) is a freely projecting prominence, which opposes its fellow and is near the opening of the genital fossa. The hamular fold is a duplicature close to the roof of the genital fossa. It is continuous with the hamular process and approaches its fellow of the opposite side. These structures,

16

THE ODONATA OF CANADA AND ALASKA

particularly the process, exhibit a great variety of forms and offer very useful taxonomic characters. The anal appendages are longer than in the Gomphidae in both sexes and are of very different form. In the male they are fitted for clasping both head and prothorax, the head being grasped by a vertical forceps of which the upper jaw consists of the two superior appendages and the lower jaw by the inferior appendage. The superior appendages are applied to the rear of the head of the female, the prothorax also being held between them. The inferior appendage is applied to the dorsum of the head, from behind the vertex to the occiput. The superior appendages are usually about as long as segments 9 and 10, and are primarily paddle-shaped, the upper surface being concave, with a carina that is often more or less elevated distally and is frequently denticulate. Numerous other modifications are found. The inferior appendage is generally triangular and dorsally concave, both longitudinally and transversely. In some genera, however, it is more or less truncate or bilobed and in Gomphaeschna it is broadly bifurcate, suggesting the Gomphidae. The females of the Aeshnidae are remarkable for their completely developed ovipositor, (pi. 7: 3,4) which resembles that of the Zygoptera closely. In this respect the Aeshnidae are the most primitive of all Anisoptera. The teredo consists of the anterior and posterior valvulae which are hard, curved, sharp-pointed structures, concealed when not in use by the genital valves. The anterior valvulae arise from the sternum of segment 8 and are partly exposed at their bases, where the basal segment, known as the basal plate, can be seen. The posterior valvulae and the genital valves both arise from the sternum of segment 9; the posterior valvulae form the dorsal valves of the teredo. They arise from the middle of the sternum of segment 9, while the genital valves arise on each side of the valvulae. In addition to serving as sheaths for the teredo they also bear near their apices a pair of styli, each tipped with a tuft of hairs. The ovipositing female of an aeshnid uses the underside of segment 10 as a fulcrum and accordingly we find various arrangements of spines to give a roughened surface. Sometimes there are many short spines, sometimes fewer long ones and in extralimital genera there may be more highly specialized devices, such as the two-pronged process of Gynacantha and the three-pronged process of Triacanthagyna. The venation of the Aeshnidae (pis. 8-10) has some characteristic features. The triangles are greatly elongated in the long axis of the wing. The fore-wing triangle is somewhat longer than the hind, and the outer side in both wings is somewhat sinuate with a forward bend near the distal angle. The triangles are usually crossed by two or three cross-veins as are also the supratriangles. In the hind wing there is a compact anal loop, enclosing two paranal cells. Vein R3 is more or less arched forward near the pterostigma and I R3 is also frequently curved forward and, except in a few genera, chiefly primitive ones, it has become bifurcate by the addition of

FAMILY AESHNIDAE

17

an anterior branch through the straightening of a series of cross-veins. The two supplements, radial and median, are well developed and may be straight and subparallel to the veins which they follow, with only one or two rows of cells between them, or they may diverge from the vein in front and converge towards it again near the wing margin, the number of rows of cells in the intervening space increasing to 4-5 or more and decreasing again. Colour-pattern. The Aeshnidae are usually brown spotted with blue or green, sometimes with yellow stripes or spots on the sides of the thorax. The abdominal spots are rather complex but are generally referable to a basic or primitive pattern, which is similar throughout most of our genera. As the pattern is repeated from segment to segment it is necessary merely to designate the spots of a single typical segment, such as one of the segments 3 to 7 (pi. 16: 9, 10). On such a segment the spots are typically arranged in two series, dorsal (D) and lateral (L) and each series consists of anterior (A), middle (M) and posterior (P) spots. Thus the dorsal series consists of AD, MD and PD and the lateral series AL, ML and PL. Except AD, which is a single spot, all the spots are typically paired. AD is usually absent or very small; MD is often differently coloured from the other spots and is rarely absent; PL often appears as a mere appendage of PD and may also be absent. AL and ML are separated merely by the transverse carina. On segment 2 AL and ML are typically united into a single quadrate or irregular spot, designated as AML. PD and PL are also united. Nymph. The nymphs of Aeshnidae (pis. 28, 29) are climbers and are found in the tangles of aquatic vegetation where they stalk their prey in a cat-like fashion. Some, however, are often found under stones, sunken wood or other waterlogged material. Such are the species of Boyeria, Basiaeschna and Nasiaeschna (pi. 28). They are easily distinguished from the members of any other family even at a very early stage. They are long, somewhat spindle-shaped, being subcylindrical and tapering posteriorly, to a long anal pyramid, which contrasts greatly with the small one possessed by the Gomphidae. The compound eyes are relatively large and much more prominent than in the Gomphidae. The antennae are six- or seven-segmented, tapering to very slender apices. The labium is flat (pi. 13) like that of the Gomphidae but considerably longer, the ligula usually obtusangulate with a closed median cleft. The palpal lobes are similar to those of Gomphidae, but the teeth or crenations on the mesal margin of the blade are much finer and more numerous than those of any of our Gomphidae. The thorax is narrower than the head. The lower ends of the propleura project above the procoxae in the form of a pair of angular processes known as supracoxal processes or prothoracic processes, which sometimes offer taxonomic characters. The legs are relatively slender and straight, having none of the modifications possessed by the Gomphidae for digging, such as the short, twisted fore and middle tibiae with their dense fringes of hair

18

THE ODONATA OF CANADA AND ALASKA

and burrowing hooks. The tarsi are all three-segmented and relatively long and slender. The abdomen is transversely subcylindrical at base and widest at about segments 5 and 6. As it narrows posteriorly it sometimes becomes somewhat tectate and develops a mid-dorsal ridge, but dorsal hooks are found only in Nasiaeschna, and even in this genus in crude form and on few segments. Lateral spines are constantly present in the species of our fauna and are most often represented on segments 5 or 6 to 9. In describing the colour pattern of nymphs mention is made of certain scar-like impressions which mark the position of attachment of muscles. These are as follows: the lateral scars, a series of pairs of smooth areas on each side of the abdominal segments, parallel to the lateral margins; the dorsal puncta, impressed dots and transverse streaks arranged in a dorsal series, two pairs on nearly every segment; the lateral puncta, a series of dark spots or dots, one on each side of every segment near the base and just mesad of the lateral scars; and the dorsolateral puncta, smaller dots mesad and distad of the lateral puncta. According to Tillyard and Fraser (1940) the family Aeshnidae is primarily divided by the character of the two veins R 4 +5 and MA into two major sections, Aeshnidi and Brachytridi. In the Aeshnidi these two veins run nearly parallel for more than half their course, separated by a single row of cells. Then MA abruptly bends backward, away from R 4+5 and at the point of deviation it gives off, on the opposite side, an oblique vein which joins the two main veins together. MA resumes its parallel course with R 4+5 but at a wider distance, there being now two rows of cells between the two veins. In the second section, Brachytridi, R 4 +5 and MA run in an unbroken curve and parallel to one another to the wing border or diverge slightly toward the distal ends. The section Brachytridi is placed first and is divided into three subfamilies of which two are represented in the Canadian fauna, namely, the Gomphaeschninae and the Brachytrinae. They are separated as follows: vein I R3 simple and unforked—Gomphaeschninae; vein I R3 symmetrically forked—Brachytrinae. In the Gomphaeschninae are included three of our genera, Gomphaeschna, Boyeria and Basiaeschna; in the Brachytrinae two genera, Epiaeschna and Nasiaeschna. The Aeshnidi contain four subfamilies, two of which are represented in our territory, Aeshninae and Anactinae. These two subfamilies are separated by Tillyard and Fraser as follows: Hind wing angulated and excavated at base in the male, oreillets present on sides of seg. 2; R3 not usually making a bend toward the pterostigma, anal triangle present Aeshninae Hind wing rounded at the base in both sexes; no oreillets on the sides of seg. 2; R3 making an abrupt bend toward the pterostigma; anal triangle absent Anactinae

FAMILY AESHNIDAE

19

The only place in the above classification where our views differ from those of Tillyard and Fraser, in so far as our own fauna is concerned, is the position of Basiaeschna. This is one of those forms that have been arrested at the parting of the ways. It resembles Boyeria in its more primitive features, particularly in the simplicity of vein I R3, of which there is no indication of a bifurcation. But, whereas in Boyeria IR3 is as straight as in the Brachytrinae and runs parallel with Rspl, in Basiaeschna there is a little divergence of these two veins from one another, with an increase from one to two rows of cells between them, followed by convergence again, and there is also a slight indication of the main feature of the Aeshnidi, in that vein MA bends slightly away from R 4+5 at the point where the number of cells in the interspace changes from one to two rows and there is the beginning of an oblique vein. Basiaeschna is, in fact, a primitive member of the Aeschna group, as is demonstrated most clearly by the form of its anterior hamules, whereas Boyeria occupies a similar position at the base of the Brachytron stem with Gomphaeschna as a somewhat aberrant ally. During early imaginal life aeshnids fly far afield, sometimes many miles from their place of emergence. Thus certain species are frequently found in cities and may even enter houses. They come to rest generally in a vertical position, on the trunk of a tree or suspended from a twig. Some habitually rest on low vegetation in the open, for example, Anax junius and Aeshna consfricta. On cold sunny days we have seen Aeshna eremita come to rest in the horizontal position on fallen logs, but this practice is exceptional. When they have returned to their breeding places, the males fly in a more or less regular beat, usually back and forth along the edge of a rush-bed or margin of a pond or stream. Some species fly chiefly during the sunny hours or during very warm weather, even when the sun is overcast. Many fly until after dusk. The two boyerias are semi-crepuscular and rest in the shade during the morning hours. Oviposition is endophytic and much resembles that of the Zygoptera. Many species oviposit in the stems of emergent plants below the surface of the water. Aeshna constricta oviposits well above the water. Boyeria, Epiaeschna and Aeshna umbrosa deposit their eggs in wet wood at the water level or a little above it and often in a horizontal position. Anax junius is peculiar among our Aeshnidae in ovipositing either singly or in tandem. The eggs may be inserted in dead floating cat-tails or in emergent plants, live or dead. When deposited early in the season, as by Anax and Basiaeschna, the eggs hatch within a month, but if deposited in late summer or autumn, as by most of our species of Aeshna and by Boyeria, the winter is passed in the egg stage and hatching takes place in the spring. KEY TO THE GENERA OF AESHNIDAE ADULTS 1. Median space with more than 1 cross-vein; sides of thorax (in our species) with 2 rounded pale spots Boyeria

20

THE ODONATA OF CANADA AND ALASKA

Median space with not more than 1 cross-vein; usually with none; sides of thorax variously marked but never with only 2 rounded pale spots 2 2. Thorax uniformly green; vein R3 making an abrupt bend towards the distal end of pt, narrowing the space immediately in front of it to less than half its width behind the proximal end of pt.; anal border of hind wing rounded in both sexes; auricles absent Anax Thorax brown marked with blue, green or yellow; vein R3 broadly curved but not making an abrupt bend forward; male with anal border of hind wing angulate and with auricles on abd. seg. 2 3 3. Vein IR 3 simple 4 Vein IR 3 forked 5 4. With two cubito-anal cross-veins on both fore and hind wings; one cross-vein behind pt.; supratriangles clear; inf. app. of male deeply forked Gomphaeschna With three or more cubito-anal cross-veins; two or more cross-veins behind pt.; supratriangle with cross-veins, inf. apps. of male triangular Basiaeschna 5. Vein IR 3 bending forward to an asymmetrical fork, the posterior branch most nearly continuing the course of the stem, usually with 3 or 4 rows of cells between IR 3 and Rspl at the widest part of the space between them Aeshna Vein IR 3 straight or nearly so, its fork symmetrical and with 1 or 2 rows of cells between IR 3 and Rspl 6 6. With a single row of cells between IR 3 and Rspl; frons very prominent; face in profile flat; sup. apps. of $ about as long as seg. 9, anal apps. of female much shorter; anterior lamina ( $ ) without a spine Nasiaeschna With two rows of cells between I R3 and Rspl, frons not unusually prominent in profile; face slightly convex; sup. apps. of male about as long as segs. 9 -j- 10, anal apps. of female somewhat longer; anterior laminae ( $ ) bearing a curved spine on each side Epiaeschna NYMPHS 1. Posterolateral margins of head decidedly angulate 2 Posterolateral margins of head rounded (rarely bluntly angular in Aeshna) , • 5 2. Abdomen transversely rounded above 3 4 Abdomen with a low median dorsal ridge 4 3. Palpal lobes of labium squarely truncate at distal ends; paraprocts about as long as 9 -f- 10, epiproct tapering to a point Boyeria

PLATE 1

Three examples of Aeshnidae: Epiaeschna héros (Fabr.), middle; Nasiaeschna pentacantha (Rambur), left; and Áeshna septentrionalis Burm., right. (Slightly reduced.)

PLATE 2

Examples of Gomphidae and Petaluridae: Gomphus (Gomphurus) vastus Walsh, above left; Gomphus (Stylurus) spiniceps (Walsh), above right; Tanypteryx hageni (Selys), below left; and Gomphus (Stylurus) scudderi Selys, below right. (Slightly reduced.)

FAMILY AESHNIDAE

21

Palpal lobes of labium tapering to a point, paraprocts longer than 9 -f 10; epiproct parallel-sided in distal half Basiaeschna 4. Median ridge of abdomen with blunt dorsal hooks Nasiaeschna Median ridge of abdomen without dorsal hooks Epiaeschna 5. Antennae longer than distance from their base to rear of head; distal margin of ligula deeply bilobed, with a V-shaped notch Gomphaeschna Antennae shorter than distance from their base to rear of head; distal margin of ligula obtusangulate, at most very slightly bilobed, with the notch closed 6 6. Compound eyes as long as their greatest width, lateral spines on 7 to 9 only; inf. app. about as long as segs. 8 and 9 Anax Compound eyes much shorter than their greatest width, lateral spines usually on 6 to 9 (rarely in 5-9 or 7-9 only); inf. app. shorter than 8 -f- 9 (usually about equal to 9 + 10) Aeshna Genus Boyeria McLachlan Ann. Mag. Nat. Hist. (6) 17: 424, 1896, a new name for Fonscolombia (pre-occupied). Type species Aeshna Irene Fonscolombe. Syn. Fonscolombia Selys, Bull. Acad. Belg., (3)5: 736, 1883; a homonym. This is a genus of four species, two in the Old World and two in eastern North America. The two North American species are medium-sized brown aeshnids, which fly along woodland streams and lake shores. They are easily distinguished from other Aeshnidae by the cross-veins in the median space and the two pale rounded spots on the sides of the thorax. These spots and the pale auricles are generally their only conspicuous pale markings, their coloration being of the type found in crepuscular species. The body is only a little hairy. The frons is moderately prominent, the compound eyes of ordinary size, the line of contiguity being about as long as the occiput. The thorax is not very massive, the legs of moderate length, wholly brown, the tibiae each with two rows of about ten slender setae, most of which are nearly twice as long as the intervening spaces. The wings are a little broader than in Aeshna or any of our other aeshnid genera. There are usually 5 cross-veins in the median space, 5 (4r-7) cubito-anal cross-veins and 9-13 cells in the anal loop; the anal triangle of the hind wing in the male has 3-5 cells, the sectors of the arculus are well separated at base; the triangles moderately elongate, usually with 5-6 cells, and the supratriangles have 4-6 cells; Rspl follows a course almost parallel with I RS, which is not bent forward, and there are 1 or 2 rows of cells between them;

22

THE ODONATA OF CANADA AND ALASKA

the pterostigmata are 6 or 7 times as long as wide, with a brace-vein, and they generally surmount 5 or 6 cross-veins. The auricles are prominent, each with about 10 minute denticles; the anterior lamina prominent on each side, blunt, the anterior hamules transverse at base, with the hamular processes directed forward and closely applied to each other; the hamular folds distant from the processes, the ridges connecting them being concealed in direct view from below. The general form of the abdomen is like that of Aeshna but is peculiar in being constricted at the base of segment 8. These insects have a characteristic flight, not very fast and somewhat jerky and butterfly-like. They do not glide nor do they hover over one spot like the species of Aeshna, or suddenly dart forwards. They fly along more or less shady streams or along lake shores, and are most active towards and after dusk. The nymphs are very dark brown or blackish and lurk under stones or bark in shallow water. They are easily known by the following combination of characters. The eyes are prominent. The posterolateral contours of the head are angular. The palpal lobes are not tapered but squarely truncate, with a small tooth in place of the end-hook and a finely denticulate mesal margin. The ligula is obtusangulate and bears a small tooth on each side not far from the middle. Lateral spines are present on segments 5 to 9 and sometimes there are very minute ones on segment 4. The last three pairs of lateral spines are rather coarse and stand out prominently from the sides of the abdomen. Key to the Species of Boyeria Adults Wings strongly flavescent, with a distinct dark brown spot at the base of each, general colour of body deep yellowish brown; mid-dorsal triangular spots of abdomen small and usually obscure in dried specimens, anal apps. of female about 5 times as long as seg. 10 (rarely short as in grafiana) vinosa Wings nearly hyaline or dull brownish, without distinct dark spots at their bases, but often darkened at the apices; general colour of body grayish brown; mid-dorsal triangular spots of abdomen large and conspicuous; anal apps. of female about as long as seg. 10 grafiana Nymphs Greatest width of prementum of labium about two-thirds of its length; lateral spines on segs. 5 to 9; epiproct distinctly shorter than the paraprocts; cerci of female nymph more than one-fourth as long as paraprocts vinosa Greatest width of prementum of labium about three-fifths of the length; lateral spines on segs. 4 to 9, the spine on 4 very minute;

FAMILY AESHNIDAE

23

epiproct as long as paraprocts, cerci of female about one-fifth as long as paraprocts grafiana Boyeria vinosa (Say). (PL 14: 1, 7; pi. 17: 2; pi. 25: 2) Aeshna vinosa Say, J. Acad. Phila., 8: 13,1839. Fonscolombia vinosa Calvert, Trans. Amer. Ent. Soc., 20: 247,1893. Boyeria vinosa Williamson, Drag. Ind., p. 300,1900. Aeshna quadriguttata Burmeister, Handb. Ent, 2: 837,1839. A medium-sized aeshnid with a somewhat tawny brown coloration, including the wings which have darker basal spots; the thorax has two clear yellow spots on each side. Male. Labium and labrum pale tawny; face tawny below, darkening above to olivaceous; postfrons greenish with an ill-defined darker median stripe, widening in front but not T-shaped; vertex and antennae brown, occiput paler, yellowish; rear of head dull brownish, darkened below occiput. Thorax brown, the dorsum darkened mesally; sides with two roundish clear yellow spots, surrounded by dark brown, legs uniformly brown; wings including veins brown-tinted, each wing with a dark brown spot at base; pt pale yellow. Abdomen fulvous, the ground colour somewhat paler in front of the transverse carina, most of the paler dorsal spots small and inconspicuous, the only clear yellow spots being those on the auricles; MD (see pi. 17: 1) forming inconspicuous median triangles on 4, 5 and 6, often obscure; PD small pairs of yellow spots on segs. 2-5, becoming obscure or vanishing rearward; AL and ML pale yellowish, usually only partly separated by the dark transverse carina; spots on 8-10 pale and irregular blotches; venter with large paired pale basal spots on 3-6. Sup. apps. (pi. 19: 2, 3) about as long as 9 -f 10, widely separated at base, widest near the apices, lateral margins nearly straight, mesal margins gently sinuate, distally abruptly narrowed to bluntly pointed apices; a dorsal ridge of uniform height extends the entire length; in profile view slightly upcurved with a distinct sub-basal inferior tooth; inf. app. about one-third the length of sup. apps., triangular with blunt and minutely bilobed apices. Female. Similar to male in colour-pattern, with pale spots somewhat smaller. Ovipositor about as long as sternum of 8, strongly curved; anal apps. longer than seg. 10, about as long as 9 but somewhat variable. In one specimen they are short as in B. grafiana, but hi other respects this individual appears to be typical vinosa. Anx $ 21-25/16-18 (15, 19); pnx 17-23/19-23 (17); primary anx 1 and 5 or 6, cells in triangle 5-7/4-6; cross-veins in cubital space 5-7/4-5; cells in anal loop 9-13; cross-veins behind pt. 4-6/4-7. Measurements. Total length $ 61-63, $ 60-63; abd. £ 43-45, $ 41-45; h. w. $ 38-41, $40-43; h. f. $ 7-8, 9 7.0-7.5; w. hd. $ $ 8.5-9.0; pt. $ 3.6-4.3/3.6-4.5, $ 3.8-4.6/4.0-5.0. Nymph (pi. 29: 3; pi. 60: 5). Brown, often appearing very dark in Me; with the following parts of the head and thorax whitish: the postocular lateral margins of the head; the lateral projecting parts of the pronotum, three femoral cross-stripes—sub-basal, median and ante-apical—two tibial cross-stripes ante-median and ante-apical; also the following abdominal markings: (1) greater part of dorsa of segs. 1-5, the whitish area breaking up caudad into two parallel stripes; (2) a median series of segmental spots, which on 5-7 are inverted V-shaped, on 8 much larger and rounded, absent on 9 and 10; (3) a lateral series of segmental spots, in transverse groups of 2 or 3 along the front or

PLATE 3

Family characters of adult head in Anisoptera: ac, anteclypeus; fr, frons; 11, lateral lobe of labium; 1m, median lobe of labium; Ir, labram; md, mandible; pc, postclypeus; 1-5, viewed from below, showing characters of mouth-parts. (1) AESHNIDAE: middle lobe of labium barely notched but with a median suture, lateral lobes wide apart (Aeshna umbrosa Walk.). (2) PETALUHIDAE: middle lobe of labium with a slight notch; lateral lobes wide apart (Tanypteryx hageni (Selys) ). (3) GOMPHIDAE: middle lobe of labium entire, lateral lobes wide apart (Gomphus lividus Selys). (4) CORDULEGASTHIDAE: middle lobe with a deep notch and a median suture, lateral lobes wide apart (Cordulegaster maculatus Selys). (5) LIBELLULOIDEA: middle lobe small and concealed by the large lateral lobes, which meet in the middle Une (Macromia ittinoiensis Walsh). (6) Aeshna palmata Hagen: front view of head, showing the various sclerites (AESHNIDAE).

FAMILY AESHNIDAE

25

>asal margins, reaching the lateral margins; muscle-scars including puncta darker than ground colour; apices or epiproct and paraprocts whitish. Prementum of labium less than 6 mm. long, its greatest width at the distal end nearly wo-thirds of its length; the expanded distal part about as long as the narrower proximal >art, ligula and palpal lobes as described for the genus. Lateral spines on abd. segs. 5 to ); those on 5 very small though distinct, the other pairs much larger, increasing but little in size caudad, rather broad and standing out prominently from the intersegmental jiembranes, those of 8 about one-third as long as the entire lateral margin of the segment Anal pyramid about as long as 9 -f- 10, epiproct a little shorter than paraprocts, aarrowing regularly to a minutely cleft apex; paraprocts tapering to slender acute apices, which are distinctly incurved; male projection somewhat more man one-third as long as spiproct; cerci of male slightly longer, those of female two-sevenths as long as paraprocts. Length 33.5-38.0; abd. 20-22; w. abd. 6.5-7.5; h. w. 7.0-7.5; h. f. 5.5-6.0; w. hd. r.5^8.0; labium 5.0-5.5. Variations. The range In length of body and hind wing, as given by Needham and Westfall (1955), is definitely greater than that of Canadian specimens, their maxima being 30-71 and 39.46 respectively. Specimens we have from Missouri and South Carolina are ill larger than those from Canada, with one exception, and it appears that in general the size of this species increases southward. Whether this change is a gradual one or involves i division into definable populations we do not know. We have one female from Algonquin Park, Ontario, whose anal apps. are short, as in B. grafiana. It is the only exception we have seen in which the difference in length of these appendages in the two species does not hold.

Habitat and range. Shady streams, preferably with some gentle rapids. N.S. to n. Ont and Mich., s. to Fla., Ala., Miss., La. and Tex. Distribution in Canada. N.S.—Truro, Pictou and Halifax counties. Que.— Ladysmith, Wakefield and other stations in the Gatineau Valley. Ont.— Huron, Peel, York, Simcoe and Leeds counties; Muskoka, Parry Sound, Nipissing, Algoma and Cochrane districts. Its northern limit, so far as known, is in the Kenogami River, northern Ont., near 50° N lat. Field notes. Williamson (1932a) said that "Boyeria vinosa is by all odds the most abundant and most widely distributed of the lotic Anisoptera east of the Great Plains. It frequents some of the smallest streams of diverse characters, as well as large and equally diverse rivers, shade being its most

26

THE ODONATA OF CANADA AND ALASKA

obvious requirement/' We first became familiar with this insect in 1903, along the Oxtongue River, Algonquin Park, Ont. (Walker, 1906). It was not only one of the commonest dragonflies seen on the trip, usually flying close to die shore and only a few inches above the water, but it quite frequently flew out to our canoe, even sometimes entering for a moment, though never coming to rest there. As Borror (1940) says, it has a "zig-zag flight a few inches above the surface of the stream." This flight, which is somewhat suggestive of Agrion or a satyrid butterfly, easily distinguishes it from Aeshna wnbrosa, the only other aeshnid that patrols our forest streams in late summer and autumn. A. umbrosa has the typical flight of its genus, a series of forward movements punctuated by periods of motionless hovering, as though suspended. Williamson (1907) observed B. vinosa on various streams in the Algoma District, Ont, north of Sault Ste. Marie, and gives an interesting picture of its habits of flight, from which we quote the following: "A common species along the streams, where its tendency to examine critically every object projecting from the water often makes its capture an embarrassing matter to the collector. More than once as I waited for an approaching male that insect suddenly left the line of flight I had mapped out for it, flew to within an inch of my legs, circled around one leg a time or two, then about the other, then about ooth, and then quietly resumed the flight along the stream oblivious to the net, which had been frantically fanned all around it ... This species is more crepuscular than any other North American Aeschnine known to me/' We would modify the last sentence to include also B. grafiana. Both species fly until increasing darkness renders them invisible. In this connection Williamson (1932a) adds "I have seen males capture their mates so late in the evening that I could barely see them on the stream where they flew." The nymphs are found under stones and other sunken materials in the stream. Emergence begins about the first or second week of July, doubtless varying with the season or locality. Our earliest dates in southern Ontario for tenerals and exuviae are July 5 and 6, but our records are extremely scanty. On Bass Creek, Lake Nipissing, Ont. (Walker, 1932b), we found exuviae in abundance on July 13 and 16, on the middle and upper part of the stream wherever there was a slight current. They were clinging to stubs, logs and even herbs and grass culms. No adults were seen on the stream, this being the teneral period, when they are scattered through the woods. After they return to the stream, the males may be seen patrolling the course from morning till evening. The time of greatest activity, however, is late afternoon and evening. According to Williamson (1932), "At rest they hang up in almost any shaded location . . . on tall herbs, bushes, or trees, in piles of large rocks, the mouths of caves, under bridges, or in culverts or buildings." "Its food so far as observed consists of minute and usually aquatic insects

FAMILY AESHNBDAE

27

which it captures with a bobbing-in-and-out flight about logs, trash, and overhanging rocks, usually along the course of a stream" (Williamson, 1932). In mating the male may seize the female over water or on land, and copulation takes place at rest. On one occasion, at our summer residence on Lake Simcoe, we observed three boyerias connected but scuffing and on capturing them we found in the net two males of B. grafiana and a female of vinosa. This happened close to the lake shore, the normal habitat of grafiana where I have seen vinosa only on two occasions. Oviposition has been described by Williamson (1934) and his description tallies with our own observations. The eggs were always inserted in wet wood a little above the waterline. On one occasion a female of this species oviposited in wood at the margin of Lake Simcoe, at DeGrassi Point, the normal habitat of B. grafiiana. We cut out a piece of the wood containing the eggs and kept it wet at room temperature throughout the winter. A few nymphs hatched in April but were more or less deformed and lived only a few days. The flight period, as indicated by our records, is two months or more (July 5 to September 22). Boyeria grafiana Williamson. (PL 9: 1; pi. 17: 2) Boyeria grafiiana Wmsn., Ent News, 18: 1,1907. Very closely related to B. vinosa, but slightly more robust, and with the general coloration a duller brown mixed with gray and yellow; the wings nearly hyaline and with only a trace of dark spots at the bases. Mainly an inhabitant of rock-margined lakes. Male. Labium reddish brown, labrum pale brown to greenish, anteclypeus and upper median part of postclypeus darker brown; antefrons olivaceous with lower margin and a median stripe paler and more reddish, or the entire face greenish with only the sutures reddish; postfrons paler behind with a diffuse median darker stripe. Thorax grayish brown, more or less varied, with reddish brown markings, as in vinosa, but with lateral spots of a slightly duller yellow or yellow-green and enclosed within a very dark area. Legs dull brown. Wings usually nearly hyaline, rarely somewhat brownish but without the fulvous tint of B. vinosa and without distinct aark basal spots; apices often infuscated; venation duller, often darker brown; pt. pale yellow. Abdomen with a variegated pattern of grayish and dark brown with dull to bright yellow spots, the brightest yellow being that which covers the auricles and the ventral surfaces of the abdomen; seg. 2 with a pair of pale dorsal transverse stripes at midlength, separated by a gap wider than in vinosa, and also with two semicircular posterodorsal pale spots; segs. 3-7 gray brown with MD spots in the form of pale yellow triangles, larger and more distinct than in vinosa, their forward angles continued ventrad along the transverse carina; area of segments behind MD darker in front and behind, paler in the middle; PD spots, if present, in 3-6 only and generally obscure; 8 with a pair of large dull yellowish spots; 9 and 10 mostly yellowish above; lateral abdominal markings as in vinosa, but the basal yellow spots (AL + ML) somewhat larger and more distinct. Ventral pattern also similar to that of vinosa. Anal apps. (pi. 19: 4) indistinguishable from those of vinosa, although the terminal abdominal segments are slightly more robust.

28

THE ODONATA OF CANADA AND ALASKA

Female. Similar colour-pattern to the male and differing structurally from G. vinosa apparently only in the much shorter anal apps., which are about as long as seg. 10. As already stated we have one female of vinosa which has short apps. as in grafiana. Anx $ 20-23/15-17; $ 20-25 (28)713-20; pnx $ 15-21/15-19, $16-20/13-20; primary anx 3 and 5 (6 or 7). Measurements. Total length $ 60-66, $ 61-67; abd. g 43-16, $ 45-50; h. w. $ 39-41, $ 42-44; h. f. $ 7.0-7.5, $ 7-8; w. hd. $ 8-9, $ 9.0-9.5; pt. $ 3.0-3.5/3.5-4.0, $ 3.4-3.8/3.5-4.0. Nymph (pi. 28: 1; pi. 29: 4; pi. 60: 6). Usually a little darker than B. vinosa with more distinct pale markings, legs with usually wider whitish cross-stripes, especially those of the tibiae; pale markings of abdomen similar to those of vinosa, except that there is usually an undulating whitish stripe extending almost the entire length of the abdomen on each side almost midway between the median series of spots and the lateral margin. Lateral spines on abd. segs. 4-7, a minute vestige on 4, the others similar to those of vinosa, the spines on 7 a uttle larger. Anal pyramid about as long as 9 -h 10; epiproct about as long as paraprocts, the apex not bifia; paraprocts stouter and less tapering than in vinosa, the apices only slightly bent mesad; cerci and male projection as in vinosa, cerci of female much shorter than those of vinosa, about one-fifth as long as the paraprocts. Prementum of labium more than 6 mm. long, its greatest width at the distal end about three-fifths of the length, the expanded distal part shorter than the narrower proximal part. Length 34-38; abd. 20.5-22.0; w. abd 6.5-7.5; h. w. 7-8; h. f. 5.8-6.5; w. hd. 7.5-8.0. Variation. The wings may be entirely hyaline or faintly brownish and are usually dusky at their apices but are frequently entirely without spots. There is no significant difference in size among the numerous specimens we have seen. The linear dimensions average a little greater than those of northern specimens of vinosa, but the southern specimens of the latter attain a slightly greater length. Williamson (1907) describes the pale markings of thorax and abdomen as blue or bluish, but in the numerous live specimens we have examined no trace of blue has ever been seen, the light spots of both thorax and abdomen always being yellow, clearest in tenerals but not changing much with age. The yellow is not as intense as in vinosa, but the main difference in the two species is in the ground colour and the abdominal pattern.

Habitat and range. Rocky shores of lakes and sometimes rapid streams, N.S. to n. Ont, s. to Mass., N.C., and Tenn. Its northern limit, so far as known, is the Nagagami River, Cochrane Dist, Ont., 15 miles from its junction with the Kabinakagami (Hudson Bay slope, 50°, 15' N lat.). Distribution in Canada. N.S.—Moser River, Halifax Co. A7.B.—Longs Creek, York Co. @t/e.-Broadview, Hull, Kirk's Ferry, Wakefield, Alcove, St. Agathe, Gocjbout. Ont.—York, Ontario, Bruce, Grey, Simcoe and Carleton counties; Muskoka, Parry Sound, Nipissing, Algoma, Thunder Bay and Cochrane districts. Field notes. This species is very similar in its habits to B. vinosa, but is mainly a lake species, although we have twice found it on swift rocky streams, flying over the most turbulent rapids. The boulder-strewn shore of Lake Simcoe at DeGrassi Point is a typical habitat of B. grafiana, the nymphs often being found under the stones close to the shore. It is never seen on any of the neighbouring streams where B. vinosa is common and conversely B. vinosa appears on the lake shore only as a very rare stray. On

FAMILY AESHNIDAE

.

29

the numerous rock-bound lakes of the Muskoka, Parry Sound and Nipissing districts, or other parts of the Canadian Shield in Quebec and Ontario, B. grafiana abounds and, in this region, at least, it appears to be the more abundant species of the two. While stationed at Go Home Bay, Georgian Bay, during several summers from 1907 to 1912, we collected full grown nymphs on and after June 4 and the first adult emerged on July 14, followed by several others during the ensuing fortnight (Walker, 1915). The exuviae are usually found on rocks, tree trunks or boathouses near the water and the tenerals fly first to a sheltered shady spot, such as a tree trunk, branch, or a cottage verandah. At DeGrassi Point every year the tenerals come to rest on the wire screen enclosing a part of the verandah of our cottage, which is but a stone's throw from the lake shore. They are usually found there in the morning and remain until late in the afternoon. Our earliest recorded dates for finding a teneral on this wire screen are une 27, 1955, and June 29, 1939, but they continue to appear throughout uly, fully mature individuals not being seen often until August. Throughout this month they are generally common, flying up and down the lake shore in late afternoon and evening, particularly about sundown, on warm evenings, and continuing until dark. During flight we are unable to distinguish grafiana from vinosa except by the .colour. Grafiana follows the shore line closely within a few inches of the water, with the same bobbing movements as described for vinosa. It follows a more or less regular beat, which may be limited to two or three yards in some little cove or recess, although more frequently it covers a much greater distance. Periods of rest are usually spent in the woods. Occasionally we have flushed them in very dark places from beneath the dense foliage of a white cedar (Thuja occidentalis) or some other dark conifer. It is apparently during the latest hours of flight that mating commonly takes place. We have seen mating pairs only rarely but almost always in the evening. We have already mentioned under B. vinosa an attempted copulation between a female of vinosa and two males of grafiana. Although we have seen B. grafiana year after year for more than four decades we have never witnessed oviposition. We suspect that it takes place well after dusk. The one time when we saw a boyeria ovipositing on our lake margin it was a B. vinosa. This was one of the two occasions when we have seen this species on the lake. The flight period sometimes extends into October in Ontario, our total range of dates being from June 27 to October 7.

}

Genus Gomphaeschna Selys Trans. Ent. Soc. London, p. 413, 1871. Type species Aeshna furcillata Say. This is an endemic North American genus of two species, both found in the eastern half of the United States. The species are rather small slender

PLATE 4

Family characters of adult head in Anisoptera: an, antenna; lo, lateral ocellus; mo, median ocellus; oc, occiput; os, eye-seam. (1) GOMPHIDAE: vertex and occiput broadly connected; transverse postocellar ridge distinct and lateral ocelli relatively large (Gomphus fraternus Say). (2) COHDULEGASTBIDAE: compound eyes barely separated; ocelli of nearly equal size, near together; occiput hairy (Cordulegaster diastatops (Selys)). (3) AESHNIDAE: eye-seam long; occiput remote from vertex; ocelli near together, the median ocellus distinctly larger than the lateral ocelli; on the postfrons, immediately in front of the vertex, is the T-spot (Aeshna umbrosa Walk.). (4) LIBELLULOIDEA: eye seam as in Aeshnidae but usually shorter; vertex arched forward, concealing the median ocellus in this view; lateral ocelh' close to antennal bases (Macromia ûlinoiensis Walsh). (5) Macromia iüinoiensis Walsh: front view of head, showing same areas as in Aeshna (pi. 3: 6); median ocellus plainly seen in this view. (6) Gomphus vastus Walsh: front view of head, showing dark transverse stripes.

FAMILY AESHNIDAE

31

aeshnids with clear wings which have few cross-veins. The superior anal appendages of the males are as long as segments 9 and 10 together and very slender; the inferior appendage is deeply bifurcate. The accessory genitalia show a definite relationship to Boyeria. The females have a very short ovipositor and short anal appendages. The venation is much reduced; the median space and the supratriangle are both clear; there are only two cubito-anal cross-veins; the triangles are shorter than usual in the Aeshnidae, that of the hind wing being more than half as wide as long and each normally has a single cross-vein. The sectors of the arculus are well separated and leave the arculus near the middle. There are usually only two secondary antenodal cross-veins between the two primary cross-veins. The pterostigma is short with a single cross-vein behind it. R3 is slightly undulate, IR 3 not forked, with only two rows of cells between it and R3 at the level of the pterostigma and only one row between IR 3 and the radial supplement. The anal triangle is two-celled and there is only one paranal cell between the anal triangle and the anal loop. The nymph has never been reared beyond the third instar (Kennedy, 1936) but an exuvia of an aeshnid nymph found near New Orleans has been referred to Gomphaeschna by exclusion and described and figured by Needham and Westf all (1955). More recently nymphs and exuviae were referred to Gomphaeschna by Bick (1957), again by exclusion of other genera. Through the kindness of Dr. Bick we received for examination two full-grown female nymphs of his presumed Gomphaeschna, and we recognized these as very close to the species figured by Needham and Westf all (1955). Their most remarkable feature, however, the long antennae, is neither described nor figured, although their length is referred to in the key. One of the two nymphs from Dr. Bick was nearly ready to transform, the wings being closely folded within their cases. The other individual, however, was younger and the wings not yet expanded and folded. The

32

THE ODONATA OF CANADA AND ALASKA

venation is, fortunately, quite distinct. Almost all of it is clearly recognizable in detail and corresponds to that of the adult Gomphaeschna as certainly as though it had been reared. The exuvia figured by Needham and Westfall is also that of a female and the cerci are like those of Bick's two specimens in being very long. Usually the larval cerci of dragonflies show a close relation in comparative length to those of the adults or the same species but this is far from being true of Gomphaeschna, since the cerci of the adult female are very short. These short cerci can be seen in the older of Dr. Bick's specimens inside the transparent larval cerci. In the form of the labium these specimens agree closely with the specimens figured in the Manual and appear to differ only in the slightly broader lateral spines and the somewhat more arcuate lateral margins of the abdominal segments. As there are two species of Gomphaeschna, both regional in Louisiana, these two species may be represented in the nymphs, but as yet it is impossible to identify the species from the nymphs. The nymph of Gomphaeschna (pi. 64: 1, 2, 3, 4) is rather slender with unusually long antennae, broad lateral spines on segs. 7 to 9 only and very long anal appendages. The two specimens we have seen are very dark and without a distinct pattern. Antennae are nearly as long as head, six-segmented, the first segment relatively stout, the second distinctly more slender but stouter than the remaining four segments, which taper slightly. The relative lengths of the segments are 8: 12: 18: 9: 18: 18. Eyes are moderate in size and prominence. Lateral and posterior margins of head nearly straight, the posterolateral angles somewhat rounded. Labrum very broad; folded labium extending back to front of mesosternum; prementum very narrow at base but widening distally to more than twice its proximal width, the lateral margins convex in the distal half; ligula deeply cleft, the two lobes well rounded and bearing a short fringe of fine piliform setae. Palpal lobes somewhat arched, rather narrow, their distal extremities truncated with the lateral angle somewhat rounded off, the distal angle produced into a sharp end-hook; mesal margins bearing a close series of small denticles of variable length. Thorax slender; prothoracic processes very low; legs long and slender. Abdomen subcylindrical, widest at seg. 6, without dorsal hooks; lateral spines present on 7 to 9 only, broad and flat, the lateral margins of these segments decidedly arcuate. Anal apps. all long and slender, epiproct as long as seg. 8, widest at base, beyond which it narrows, first rapidly, then gradually throughout most of its length to the pointed apex; paraprocts slightly longer than epiproct, tapering to acute apices; cerci shorter than the other appendages but unusually long, slender and taper-pointed. Ovipositor extending from base of seg. 9 to middle of 10, its width at base equal to about four-fifths of its length, narrowing with curved margins to the apex. Length 29-35; abd. 20-25; w. abd. 6.3: w. hd. 6. The longer nymph is overextended.

FAMILY AESHNIDAE

33

These nymphs were determined as Gomphaeschna sp., one specimen by G. H. Bick, the other by Minter Westfall. The prementum of the labium is distally very wide, its greatest width being more than twice the width at base and equal to at least two-thirds of its length. The ligula is deeply notched, broadly bilobed and "fringed with short scurfy hairs" (piliform setae). The palpal lobes are rather narrow, the distal ends truncated and prolonged mesad into a very prominent end-hook. The mesal margins appear to be relatively coarsely denticulate. The above characters can be seen in the illustration in Needham and Westfall's Manual, reproduced from photographs by Dr. R. S. Hodges. Only the last five segments of the abdomen are shown in one of these photographs, the other figure showing the labium. Needham and Westfall, however, state that the hind angles of the head are rounded. The legs are pale with faint rings of darker colour near the knees. The length of the nymph is about 30 mm. "The abdomen is widest on segment 6, with strong outstanding lateral spines on 7 to 9 only. These spines are of nearly equal size." Gomphaeschna furcfflata (Say). (PL 10: 1; pi. 14: 2, 9; pi. 17: 3; pi. 19: 1; pi. 25:1) Aeschna furcillata Say, J. Acad. Phila., 8: 14,1839. Gomphaeschna furcillata Selys, Trans. Ent. Soc. London, p. 413, 1871; Bull. Acad. Belg., (8) 5: 733,1883. A small slender aeshnid with a brown and greenish colour-pattern and very open venation; the male with a deeply forked inf. app., the female with a small ovipositor and very short anal apps. Male. Labium very dark greenish gray, nearly black on the middle lobe; labrum obscure greenish with the free edge and basal transverse line black; face obscure greenish; anteclypeus, postclypeus and antefrons each darkened in the middle; postclypeus and frons pale on the sides and above, except in the middle, where a large median black triangle extends forward from the vertex, its blunt apex reaching the front margin, where it joins a transverse black line; vertex black with a median yellowish spot, rear of head black. Pterothorax light brown, striped with paler green or greenish yellow; antehumeral green stripes near the median carina, each dividea into an anterior elongate stripe and a posterior short transverse spot, close to the ante-alar ridge, sides green and brown, the green predominating and divided into areas as shown on pi. 14: 2, one of the features being the green triangle on the anterolateral corner of the metepisternum. Legs brown, darkened towards the joints; wings hyaline; pt. brown. Abd. seg. 1 and 2 brown with a greenish patch on die sides, including the yellowish green auricles; 2 above with a basal triangle (AD); a middle pair of small spots (AL) and a posterior pair of large spots (PD). Remaining segs. up to 9 all with PD paired and triangular; MD smaller, paler, diminishing caudad to mere dots on 6; AD triangular on 3 and 4, becoming smaller and ill defined to 6; lateral spots AL and ML only, decreasing to 7; AL subquadrate, ML long and narrow. Head rather large, antefrons prominent and very rugose in the middle. Pterothorax covered to a moderate extent with grayish hairs, abaomen with segs. 1 and 2 fairly stout,

34

THE ODONATA OF CANADA AND ALASKA

3 moderately constricted, then slender, narrowing gradually to 10. Sup. apps. about as long as 9 H- 10, very slender but widening gradually a very little to rounded apices, decidedly bowed and arched. Inf. app. half as long as sup. apps., broadly bifurcate. Anterior lamina with prominent straight spines; anterior hamules much as in Boyeria but the comb of stiff setae, the hamular processes with pointed apices close together and directed cephalad; vesicle of penis with a pair of curved projecting processes. Female. Of similar size and proportions except in the greater thickness of the abdomen and the very short anal apps. Relative lengths of segs. 7-10 approximately 7.2/6/5/2, seg. 7 being about 3.6 mm. long; segs. 8 and 9 slightly thickened; posteroventral margin of 10 beset with numerous short setae; length of ovipositor 2.5; of anal apps. 1.25. Colourpattern similar to that of male. Anx 3 11-14/7-10, 9 13-14/7-8; pnx 3 5-8/6-10, $ 6-7/7-8. Triangles with 1 cross-vein, rarely 2; anal loop $ with 4-5 cells, rarely 3; and triangle with 2 cells, rarely only 1. Measurements (1 9 only). Total length $ 53-56, 9 50; abd. $ 35-39, 9 36; h. w. $ 32-34, 9 32; h. f. $ 7.0-5, 9 7; w. hd. $ 7.0-7.8, 9 7.4; pt. $ 1.8-2.0/2.0-2.2, 9 2.0/2.4. Nymph. Only the first three instars of Gomphaeschna furcittata have been reared (Kennedy, 1936), but we now know that the characters of the final stage ascribed to Gomphaeschna, by Needham and Westfall (1953), were correctly referred to this genus (seep. 31).

Habitat and range. Sphagnum bog ponds. Fla., Ala., Miss, and Ark., n. to N.S., Me. and Mich. Distribution in Canada. N.S.—South Milford, Annapolis Co. Field notes. This species was first taken in Canada in 1934 at South Milford by J. H. McDunnough and a good series of males obtained. They were flying over a road and had doubtless not yet reached the pairing stage. On July 8, 1940, we visited the same locality and discovered at the foot of a wooded slope an extensive floating bog with a series of irregular and connecting ponds. Along the edge of the bog, at the foot of the slope, was the usual "moat" or ditch, and here we found males of G. furcillata flying up and down. Although they came to rest occasionally on the slender trunks and branches of the gray birch (Betula populifolia), it was difficult to approach them on account of the presence of these branches. By the time we had taken two males all the others had disappeared. Next morning we were back again at the same spot and were pleased to find that Gomphaeschna was now flying over the open bog and was easier to net than most aeshnids. We took eight males but no females or exuviae. The bog was visited a third time on July 16, but not a single Gomphaeschna was seen (Walker, 1942). Kennedy (1936) found G. furcillata about a small "sphagnum bog at Rigwood, on the highland, near Ithaca, New York. On June 27,1917, a female was seen to settle and oviposit in the soft rotten part of the root of a small tree in the middle of the sphagnum area. . . . Over an area three inches long and two inches wide she tried various spots with the tip of her abdomen and eventually inserted her ovipositor more than thirty times. Except that the tips of the eggs were visible and all had their sharp points up they

FAMILY AESHNIDAE

35

showed no particular arrangement. Thus her actions in oviposition were those of aeshnid females in general." A number of these eggs were hatched and reared through two stages. A single one reached the third stage. In all three stages seg. 9 bears very small lateral spines, whereas there are none on seg. 8 or any of the segments in front of 8. The arrangement of lateral spines is thus strikingly different from that of the final instar. Genus Basiaeschna Selys Bull. Acad. Belg., (3) 5: 735,1883. Type species Aeshna Janata Say. A monotypic North American genus having the appearance of a small Aeshna but with narrower wings and more primitive venation. The median space is clear, the arculus is about equally divided by the sectors, the triangles are rather short, that of the hind wings having the base approximately half as long as the anterior side. Both triangles and supratriangles usually have each two cross-veins, rarely only one. Tnere is one paranal cell between the anal triangle of the male and the anal loop. R3 curves broadly forward somewhat proximad of the pterostigma widening the space between it and IR 3 , which space contains three rows of cells at the level of widest separation. There are also three rows of cells between I RS and Rspl, which converge distally until there is only one separating row of cells before the wing margin is reached. I R3 is not forked. The pterostigmata are rather long and narrow and there are usually three of four cross-veins in the space behind each pterostigma, not including the brace-vein. The compound eyes are smaller than in Boyeria or in most species of Aeshna, the line of contiguity being scarcely longer than the occiput. The form and colour pattern of the abdomen are very nice that of Aeshna. The nymph is like that of both Boyeria and Aeshna, resembling the former in the decided angularity of the posterolateral corners of the head and in having lateral spines on segments 5 to 9 of the abdomen. The slender pointed apices of the palpal lobes of the labium are not characteritsic of either of the other genera but are found in one of our native species of Aeshna, A. constricta. The very long and slender paraprocts are a distinctive feature of Basiaeschna. This genus is strictly nearctic, its range being North American east of the Great Plains, although it has been taken in Oklahoma and Texas. Basiaeschna Janata (Say). (PL 9: 2; pi. 14: 3, 8; pi. 19: 5, 6; pi. 25: 5) Aeschna Janata Say, J. Acad. Phila., p. 13,1839. Basiaeschna Janata Kellicott, Odon. Ohio, p. 81,1899. A rather small early aeshnid of streams and lakes with the oblique yellow stripes on the sides of the thorax.

36

THE ODONATA OF CANADA AND ALASKA

Male. Face and mouth-parts olivaceous, sometimes uniformly so, or with the labrum paler and the labium brownish. Postfrons with a T-spot, the stem parallel-sided; vertex and occiput usually olivaceous; rear of head dull yellowish. Pterothorax dark reddish brown with a pair of green dorsal stripes, which are forwardly curved and divergent and generally obscure in dried specimens, and two conspicuous, oblique yellow lateral stripes, each edged with black, the first (mesepimeral) stripe widening and obliquely cut below, the second (metepimeral) with the upper third bent somewhat downwards. Legs brown, darker on the flexor surfaces, with black spines. Wings slightly tinged with brown, with a dark brown spot at the base of each; pt. and veins reddish toward and including the costal margin, elsewhere dark brown. Abdomen brown with blue spots surrounded by black, the patteiji of spots similar to the typical Aeshna pattern, i.e., on most of the segments, AL, ML and PD of the usual size, AD absent and MD a small pair of dorsal triangles, obscure in dried specimens. Compound eyes somewhat smaller than in most species of Aeshna; the median line of contiguity being little longer than the occiput; legs of average length, the hind femora extending back as far as the hind margin of seg. 1 of abdomen. Abdomen shaped as in Aeshna, with a marked constriction at seg. 3, widening behind to 7 and narrowing again slightly to 10. Accessory genitalia like those of Aeshna (cf. A. mutata) rather than Boyeria. Sup. anal apps. about as long as 9 -f- 10, in profile showing two bends, a short downward oend from the extreme base and a long upward bend slightly beyond the middle; viewed obliquely from above they appear slender from base to the second bend, where they are suddenly widened mesocaudad, then narrowing slightly to the bluntly rounded apices. Inf. apps. about half as long as sup. apps., long triangular and upcurvea as in figure. Female. Apart from the usual differences in form of hind wings and abdomen, the two sexes are much alike. Colour-pattern similar but abdominal spots varying from blue to green. Segs. 8 and 9 deeper than the others, except seg. 2. Relative length of 7-10: 55/40/30/17. Apps. 4-5 mm., or slightly shorter than seg. 7. Anx $ 16-19/12-14, 9 17-19/12-14; primary anx $ 9 1 and 6 or 7, pnx $ 13-17/12-14, 9 13-16/13-16; cells in anal loop of hind wings 6-8; cross-veins behind pt. 3—4/3-5. For other venational characters see description of genus. Measurements. Total length $ 53-64, 9 57-64; abd. $ 37.0-43.5, 9 40-46; h. w. $ 32-40, 9 34.5-40.0; h. f. $ 6.4-8.0, 9 6.5-7.5; w. hd. $ 9 8-9; pt. $ 2.5-3.0/3.O3.7, 9 2.7-3.4/3.3-3.7; apps. 9 4.0-4.7. Nymph (pi. 28: 2). Eyes prominent; head widest across posterior third of eyes; lateral margins of head straight, slightly convergent caudad, posterolateral corners obtusangulate; hind margin of nead slightly concave in the middle; antennae 7-segmented; prementum of labium widest at about the distal fifth, its greatest width equal to about five-sixths of its length, width at base slightly more than half the width at the distal articulation; sides in proximal four-sevenths nearly straight and slightly divergent, distally distinctly arcuate. Palpal lobes with blades tapering and curving to bluntly pointed apices. Wing-cases reaching a little beyond the base of abd. seg. 5. Abdomen slender at base, widening as far as seg. 7, narrowing beyond, especially on 9 and 10. Lateral spines on 5 to 9 and often rudiments on 4, standing out prominently from the intersegmental membranes, those of 7 to 9 projecting beyond the base of the next segment following. Paraprocts very long, straight and acute, being about a third longer than 9 -f 10 and shorter than 8 + 9; epiproct about five-eighths as long as paraprocts, parallel-sided except towards base, deeply bifid at apex; cerci longer than 10, nearly as long as 9, slender with sharp apices; male projection distinctly shorter than cerci; ovipositor reaching posterior end of seg. 9. Colour-pattern variable, exuviae usually pale. Head with lateral margins pale; legs with alternate dark and pale annuli very distinct; femora with base and apex dark and with two wider dark annuli between; tibiae with basal, apical and one intermediate dark annulus. Abdomen with puncta and lateral muscle scars darkened and with the

FAMILY AESHNIDAE

37

following pale areas: dorsal surface of basal segments, interrupted by the dark puncta and dividing about the apices of the wing sheaths into two bands or two series of basal spots; a large dorsal area on 9 or 9 and 10, and a series of laterobasal spots, two or three on most of the middle segments in general alignment with the lateral musclescars. Length 31-40; abd. 21-27; w. abd. 6.0-7.5, h. w. 6.4-7.5; h. f. 6.8; w. hd. 7.2-8.5. Variations. We have noted little variation in B. Janata except in size. The largest specimens, measuring 64 mm. in over-all length in both sexes, came from the vicinity of Favourable Lake, Ont., which is also at the northern limit of its known range. We have also examined one male and one female of about the same size from St. Louis Co., Minn., June 25 and 27, 1957 (coll. W. V. Balduf), received from Mrs. L. K. Gloyd. Specimens from the Maritime Provinces appear to average a little smaller than those from Quebec and Ontario.

Habitat and range. Small forest streams with riffles or a gentle current, and lakes. N.S. to n. Ont., s. to Fla., Ala., Tenn. and Tex. Distribution in Canada. N.S.—Annapolis, Halifax, Pictou and Inverness (Cape Breton I.) counties. N.B.—York, Sunbury, Queens and Charlotte counties. Que.—Iberville, St. Hyacinthe, Richelieu, Lake St. Peter, Montreal, Hull, Wakefield, and other stations in the Gatineau Valley, Nominingue, Mont Tremblant Park. Ont—Essex, Haldimand, Welland, Huron, Wellington, York, Simcoe, Victoria, Peterborough, Hastings, Frontenac, Leeds, Lanark, Renfrew and Carleton counties; Muskoka, Parry Sound, Nipissing, Thunder Bay and Kenora districts, including the Patricia section. The northern limit, so far as known, is in the vicinity of Favourable Lake in the Patricia section of the Kenora Dist., near the Manitoba boundary (53°5(y N) (Walker, 1940). Field notes. This small aeshnid is somewhat like the two species of Boyeria in habits and haunts but flies during the first, instead of the second half of summer. The nymphs cling to the undersides of stones or waterlogged wood near the shore, like those of Boyeria, but are less restricted to visibly moving waters, being sometimes found in small recesses or quiet parts of a stream, where a few rushes and other emergent aquatic plants grow, there being in such places usually plenty of mayfly and other insect larvae. Basiaeschna nymphs always live in well-aerated waters, never inhabiting marshy places to any extent. They are, however, found in lakes as well as streams, but chiefly in small lakes or sheltered bays of larger lakes. On Lake Simcoe they are found very sparingly along the boulder-strewn shore of DeGrassi Point, where Boyeria grafiana is commonly found later in the season, but a few are generally present at the outlet of a small stream, on a relatively quiet bay where the water from the lake washes in and out to a limited extent. At Go Home Bay, on the Precambrian shore of Georgian Bay, we reared many of the nymphs in 1912 (Walker, 1915). Full-grown nymphs were found on our arrival on May 20 and continued to be found until June 10. The first adults seen were those which emerged in the laboratory on June 8. Adults were taken until June 25, but were not noticed after this date. At the

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THE ODONATA OF CANADA AND ALASKA

same locality in 1907, however, we captured specimens frequently until July 17. The exuviae may be found, like those of Boyeria, on stumps, wharves and boathouses, sometimes at a height of six feet, but they also occur on the stems of emergent plants. In the Toronto region emergence begins earlier than on Georgian Bay. We saw a male patrolling the Humber River near Kleinburg on May 27, 1939, and at Lake St. George, twenty miles north of the city, on May 30. These individuals must have emerged a week or more earlier for, after emergence, they wander over the countryside as other aeshnids do. At Go Home Bay, for instance, we found them in the rocky open woods, within a few hundred yards of the water. The mature insects, returning to the stream, or lake, patrol the shore somewhat after the manner of Boyeria, although they fly at a greater speed and at a somewhat greater height usually several feet above the water or shore. They are active during the day but also fly sometimes until well after sundown. On a recent occasion at Limberlost, Ont, we saw one flying at dusk up and down a sloping road, which descended to a marsh-bordered channel. The flight was swift, somewhat erratic, and when the insect was finally captured, we were somewhat surprised that it was a Basiaeschna. B. Janata is as common in the Maritime Provinces as in Ontario and Quebec. The season is apparently somewhat later there, as we found it common about the middle of July, a time at which the season is usually over in southern Ontario; our latest date is from the Margaree River, Cape Breton Island, N.S., namely, August 9, 1948. Our latest date in southern Ontario is July 17 (Go Home Bay), but in the Favourable Lake region in northern Ontario the latest record is July 29 (Walker, 1940). We have only rarely seen a female ovipositing, Needham (1901), however, watched the process carefully several times at Saranac Inn, N.Y., and from his account we quote the following: In each instance observed the eggs were deposited in leaves of a species of bur-reed, Sparganium, which where it grew in the deeper water of the creek, trailed the long leaves on the surface of the stream. The female flitted from plant to plant, making a few thrusts with her ovipositor into each at the water-line and then settled and balanced herself carefully on a long floating leaf. . . . Backing down into the water till the abdomen was wholly submerged, she began thrusting with her ovipositor, first to right and then to left, moving forward a little between thrusts, leaving behind a double row of punctures as regular as the neatest double stitching that might be done with a needle. Several such double rows of eggs were placed in the tissues of this leaf before she left it.

Needham and Westfall (1955) also report this insect as ovipositing in floating dead leaves or cat-tails and trash. We have seen a female Basiaeschna alight upon a very small growing leaf of the white waterlily only barely large enough to support her. She lowered her abdomen into the water and curved it under the leaf into the lower surface of which the eggs were thrust. She remained only a few seconds, however, the leaf, a solitary one, probably being too small.

FAMILY AESHNIDAE

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Genus Nasiaeschna Selys Included in a paper "Odonaten aus Neu-Guinea" by F. Foerster, in Termeszetrajzi Fiizetek, v. 23, Budapest; Selys' description in French. Type species Aeschna pentacantha Rambur. A monotypic genus of eastern North America. The name is derived from the prominence of the frons, which is one of the marked features of the genus. The vertex is also prominent and bilobed and the occiput somewhat carinate. The venation is typical of the Brachytrinae in which I RS is symmetrically forked and its course is clearly paralleled by Rspl, which throughout most of its length is separated from I R3 by only a single row of cells. R4 and MA are also separated by a single row of cells, and a number of other spaces between longitudinal veins are separated by a single row. The median space is clear, there are usually three or four cubital cross-veins, a wide three-celled anal triangle in the male, which is separated from the anal loop by one paranal cell, there being normally six paranal cells in the hind wing and six or seven in the fore wings. The triangles are moderately long and usually divided into three or four cells; the supratriangles are similarly divided. The pterostigmata are moderately large with normally three or four cross-veins behind that of the fore wing and four or five behind that of the hind wing. The abdomen tapers almost regularly caudad, segment 2 being little swollen and 3 very slightly constricted. The superior appendages of the male are smaller and closer together than in other regional aeshnid genera. The appendages of the female are also very short. The genitalia reveal at once these brachytrine affinities, the anterior hamules having the hamular processes far in front of the hamular folds, and the processes similarly divided into a proximal pair of very prominent knobs and a distal pair of blades which are directed dorsad, i.e., towards the floor of the genital pocket, and their mesal margins are almost contiguous. The anterior lamina consists chiefly of a pair of rounded knobs which are devoid of the usual spines. The nymph is a strange-looking creature. It is sluggish, and heavily built, with broad, flattened femora and angular head; rapidly narrowing behind, and an abdomen with steep sloping sides bearing a few stumpy dorsal hooks. The dorsum of the head is divided into two planes, a larger anterior plane, bearing the small but prominent eyes and a smaller posterior plane, sloping ventrocaudad to the concave hind margin. The junction of the two planes is marked on each side by a prominent, elevated angle and there are other less prominent angles, where the sides of the second plane meet the concave hind margin of the head. The antennae are seven-segmented, the ratio of segment lengths being 15/12/23/15/13/10/8. The labial mask is of moderate width, proximal half with nearly parallel sides, distally as broad as long with strongly arcuate sides, the blades of the palpal lobes being slender with bluntly rounded apices. The legs are rather short, the femora strongly

PLATE 5

Some general features of the legs in Anisoptera (CB, comb; K, keel): (1) Cordulegaster diastatops (Selys), male, right fore tibia, showing vestigial keel at the distal extremity; (2) Gomphus exilis Selys, male, left fore tibia, showing tibial keel and spines; (3) Gomphus exilis, male, ventral view of left fore tibia, showing comb and tibial keel; (4) Aeshna umbrosa Walk., male, ventral view of left fore tibia, showing comb but no keel; (5) Aeshna umbrosa, hind leg of male; (6) Gomphus exilis, hind leg of male; (7) Gomphus exilis, hind leg of female, showing much longer spines on femur, tibia and tarsus than in male; (8) Gomphus, tarsal claw, typical of most Anisoptera; ( 9 ) Macromia, tarsal claw, typical of Macromiidae.

FAMILY AESHNIDAE

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curved and flattened, their outer surfaces with three longitudinal ridges. The wing-cases reach little beyond the base of segment 4. The abdomen is long, flattened below, subcylindrical above in the anterior segments, a middorsal ridge appearing on segment 4 and becoming increasingly sharp caudad, segments 7 to 10 being distinctly tectate with vestiges of dorsal hooks on 6 and 7 and distinct blunt hooks on 8 and 9. Lateral spines are present on 4 to 9, mere vestiges on 4, but increasing in size and caudad and also becoming relatively broad on 9. The anal appendages are straight and blunt, the epiproct about 1.5 times as long as segment 10 (see also under N. pentacantha). Nasiaeschna pentacantha (Rambur). (PL 1; pi. 14: 4; pi. 19: 8,9; pi. 25:3) Aeshna pentacantha Rambur, Inst. Neur., p. 208,1842. Nasiaeschna pentacantha Needham, N.Y. State Mus. Bull., 47: 467, 1901. A large aeshnid with a very prominent front, which is blue above, and an abdomen which tapers more evenly than usual from base to tip and bears small appendages. It is a southern species and is rare in Canada. Male (colours of fresh specimen). Face light gray with a slightly bluish tinge, deepening to dark brown on the irons next to the eyes; postfrons blue with a diffuse dark band where it meets the vertex; eyes bright blue; vertex and occiput whitish; rear of head obscure brownish, black next the occiput. Pterothorax reddish brown, rather pale, with grass-green stripes, of which the dorsal stripes are each about as broad as the median brown space, forwardly divergent, each with an upcurved lateral offshoot from the posterior end. Sides with two broad green stripes on a brownish gray ground colour, very inconspicuous in dried specimens. Legs brown to black, femora brown darkening distally, tibiae and tarsi black. Wings hyaline, veins chiefly blackish, but costa, subcostal cross-veins and oblique vein pale yellowish. Abdomen (pi. 17: 6) greenish black with dorsal segmental areas bluish green, these areas divided oy the transverse carinae, narrowed behind, with two or three black lateral indentations. Sup. apps. black, inf. app. paler. Face nearly flat, the large postclypeus nearly enclosed by a crescentic ridge; frons very prominent, the antefrons rugose and margined above by a sharp ridge overhanging a deep, narrow groove. Postfrons unusually long (pi. 14: 4), vertex elevated and bilobed, occiput somewhat carinate. Legs of moderate length; hind femora extending to the middle of abd. seg. 2; hind tibiae distinctly shorter and somewhat bowed; tibial spines very short; middle tibiae also de-

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THE ODONATA OF CANADA AND ALASKA

curved distally. Abdomen little inflated at seg. 2 and only slightly constricted at seg. 3 decreasing steadily in width from 2 rearward; 10 without a dorsal crest. Sup. apps. about a tnird longer than seg. 10, rather near together and of simple form, parallel, slightly arched, the lateral margins nearly straight, mesal margins approximated beyond the middle, thus widening the appendage here, apices bluntly rounded, dorsal carina absent; inf. app. nearly three-fourths as long as sup. apps., triangular, upcurved, more than twice as long as basal breadth, grooved above and below, apex minutely bilobed. Anterior lamina without the usual two spines; hamular processes each with a pair of very prominent lateral knobs, from the bases of which are produced anterodorsad a pair of prominent almost contiguous blades or rami (hamular folds extending well caudad of the processes, with which they are connected by parallel ridges (pi. 25: 3)). Female similar to male in size and proportions, except in the stouter abdomen and the genitalia. Markings in our single female not appreciably different from those of the male. Anal apps. about as long as seg. 10. Anx $ 17-19/11-13, $ 18-19/11-13; primary anx usually 1 and 5-7; pnx $ 14-18/15-19, $ 15/15-16. For other venational features, see under description of genus. Measurements (3$ 1$ of Canadian specimens). Total length $ 68-69, $ 66.5; abd. $ 46-49, $ 48; h. w. $ 43-46; $ 46; h. f. $ 9-10, $ 9.5; w. hd., $ 9.5-10.0, $ 9.3; pt. £3.2-3.5/3.8-4.0, $ 4.5/5.0. Of three males from Florida, one measures 71 in. over-all length, but the other measurements do not exceed those of Canadian specimens. The other specimens also fall within the above measurements. Nymph (pi. 28: 3). The structural characters of the nymph have been dealt with under the generic description. The coloration is dark, without a distinct pattern except on the legs, which are dark grayish brown, the femora and tibiae each with two narrow whitish cross-bars, those of the femora in the distal half, or median and ante-apical, those of the tibiae nearer the base and apex respectively; tarsi dark with a wide white band around the basal half of the third segment. Length: 43-46; abd. 31-34; w. abd. 8.Q-8.5; h. w. 8-9; h. f. 6.0-6.5; w. hd. 8.5-9.0.

Habitat and range. Woodland streams, or sheltered bays and channels. Fla. to Tex., n. to Iowa, Ont, s. Que., N.H., and Mass. Distribution in Canada. Que.—Bell Lake, near Wakefield, Labelle Co. Ont.—Welland, Lincoln, Simcoe, Victoria and Lennox-and-Addington counties; Muskoka and Nipissing districts. Field notes. Our very limited experience in collecting this rare insect seems to indicate that it inhabits slow streams, sheltered bays into which a stream debouches or lakes formed by the expansion of a stream. The only female that we have taken was captured on the Welland River, Ont., near Hewitt. The stream was about 50 yards wide at this spot and was very muddy with a deep soft bottom. It was fringed with shrubs and small trees, and among the commonest emergent plants were Sagittaria and Sparganium. There were also floating plants such as spatterdock (Nuphar). The other localities where we have observed Nasiaeschna were very different from the Welland River. Our first capture was made at Go Home Bay, and the habitat here appeared from later experience to be fairly typical. The single male was taken while flying over the marshy outlet of a small stream at the inner end of one of the many long-sheltered bays in this region. We had

FAMILY AESHNIDAE

43

been other individuals at this locality earlier in the season without recognizing the species. On July 12, 1929, we captured it at a very similar locality at the headwaters of the French River, and on June 20,1933, while collecting in the Gatineau Valley, Que., we met with Nasiaeschna for the third time at Bell Lake, a small rock-margined lake which is an expansion of the Lapêche River, again capturing only a single male. According to Needham and Westfall (1955) the nymphs of this peculiar insect "inhabit woodland streams and are to be found clinging to dead wood and sticks and among fallen leaves and trash along the edges of the current." Very few nymphs have been found in Canada and all in the vicinity of Georgian Bay within or immediately south of the Muskoka District. One of the two that were taken at Go Home Bay in 1907 was Round clinging to the writer's paddle while he was passing by canoe through the outlet of a small lake into the open bay. The other was dredged from among the rushes along the edge of a sand-bottomed channel in which a more or less distinct current was usually perceptible (Walker, 1915). Although the nymphs of Nesiaeschna are easy to keep in aquaria, our few attempts to rear them were unsuccessful owing to accidents. One was kept alive through the winter, having reached the final larval stage before winter set in. We have never observed emergence and have only once found an exuvia. This was discovered on June 29, 1945, on a sheltered bay at the southern end of Lake Mazinaw. It was clinging to a wooden stub on the shore and was three or four feet above the water level. In Indiana, according to Montgomery (1947), the flight period of N. pentacantha begins during the first third of June and continues until the last third of August, reaching its height early in July. Most of our few records are from the second half of June, the known period being from June 20 to July 16. The specimens collected were all mature and we have therefore no definite idea as to when emergence begins. Genus Epiaeschna Hagen Proc. Boston Soc. Nat. Hist., 18: 86, 1877. Type Aeshna heros Fabricius. A monotypic genus peculiar to North America, the single species, E. heros Fabr., being among the largest of North American dragonflies. It is clearly related to Nasiaeschna and the palearctic genus Brachytron, as indicated by certain venational and genitalic characters of the adult and also some of the larval features. Among the venational characters are the following: Vein I R3 is nearly straight to the point of forking, which is symmetrical and is at the level of about the fourth costal cell before the pterostigma in each wing; between the forks are about four rows of cells; the radial supplement is straight, diverging a little from the stem of I R3, there being two or two and part of a

44

THE ODONATA OF CANADA AND ALASKA

third between these veins, behind the point of forking but narrowing to on< row at the wing margin. There are three rows between MA and the mediai supplement. Both triangles and supratriangles are long and divided inb several cells, i.e., 5-7 in the triangle of the fore wing, 3 to 5 in that of hint wing; and usually there is a vein perpendicular to the base of the triangl* in the fore wing. The outer side of the triangle is sinuate and the trigona planate is clear and well developed. There are typically two rows of cell' in the anal loop. The anterior hamules are of the Brachytron type, characterized by th< wide separation of the hamular processes from the hamular folds, these being connected by lateral ridges and by the form of the hamular pro cesses, which are divided into a pair of prominent transverse knobs, eacl with a straight and acute blade, which is directed towards the floor of tht genital fossa and is almost contiguous with its fellow along the median line. The anterior lamina bears a pair of curved spines and in this feature Epiaeschna differs from Nasiaeschna in which the spines are wholly absent The nymph is similar to that of Brachytron and Nasiaeschna in that it ha? a distinct median ridge on the more posterior segments, becoming sharper posteriorly and the segments more compressed. There are no dorsal hooks, however, Epiaeschna resembling Brachytron in this respect and differing from Nasiaeschna. In all three of these genera the labial mask widens strongly distally and the blade of the palpal lobe is little or no wider than the base of the movable hook; the apices of the blade are more or less truncate. There are other minor characters which confirm their relatively near relationships, but these are the more noticeable ones. Epiaeschna heros (Fabricius). (PL 1; pi. 14: 5; pi. 17: 5; pi. 19: 7; pi. 25: 4) Aeshna heros Fabricius, Ent. Syst. Suppl., p. 285,1798. Aeschna heros Hagen, Syn. Neur. N. Amer., p. 128,1861. Epiaeschna heros Karsch, Ent. Nachr., 17: 286,1891. Aeshna multicincta Say, J. Acad. Phila., 8: 9,1839. Largest of Canadian Odonata, often over 90 mm. long; brown and green with tapering abdomen and long anal appendages, widely distributed in the United States, but restricted in Canada to southern Quebec and Ontario. Male. Labrum and mandibles reddish brown, face brown below, grading above into green or olivaceous on postclypeus, deepening to dark brown on the antefrons particularly in the groove below the anterior transverse ridge, postfrons reddish brown, darkened in the middle, often with a pale green spot on each side. Eyes bluish in life, though not so brilliant as in Nasiaeschna. Occiput and a broad spot on vertex pale; rear of head pale dull brown, black above; pterothorax reddish brown, striped with green as follows: dorsal stripes half as wide as the median space, each stripe with a straight lateral edge and a sinuate mesal edge, with a widening just below the middle and at the rear end; sides with two straight oblique stripes, each about 1.5 to 2.0 mm. wide. Legs black with proximal parts of fore femora brown. Wings hyaline or slightly brownish; veins chiefly blackish but costa, subcostal and Rj cross-veins up to and including subnodus pale

FAMILY AESHNIDAE

45

yellowish; pt. brown. Abdomen greenish black with narrow pale green annul! connected on each side by a longitudinal green line; segs 1 and 2 obscure greenish gray, 3 to 5 with basal, middle and apical semi-annuli, AD, MD and PD widest on 3, narrowing on each successive segment, MD absent from 7 or 8 caudad, 8-10 almost devoid of pale spots. Head large, eyes a little more globose than in most of our Aeshnidae; face vertical, in profile slightly convex with a marked groove beneath the transverse frontal ridge. Hind femora not quite reaching as far back as the auricles, hind tibiae three-fourths as long as femora, nearly straight, their spines almost twice as long as width of tibiae measured in profile. Abdomen tapering from seg. 2 to 10; seg. 2 little inflated and 3 scarcely at all constricted; 10 with a dorsal tooth. Sup. apps. slightly longer than 9 -f 10, their bases well separated and slightly bent, as viewed dorsally, widening from proximal fourth, labial margin a little convex, mesal margin sinuate, distal third with a high dorsal crest, terminating at blunt apices; lateral view showing prominent postbasal ventral tubercle, followed by a sharp constriction, then deepening and curving upward to blunt apices. Inf. app. about half as long as sup. apps., little upcurved except at base, narrowing in proximal four-fifths, then slightly widening to the bilobed apex. Anterior lamina with a pair of strongly curved spines; hamular processes consisting of a pair of short transverse knobs and two pointed blades, contiguous in the middle line and directed dorsad and cephalad. The hamular folds are farther removed from the processes than in Nasiaeschna and not approximated to each other. Female. In size and colour-pattern quite similar to the male except that the abdominal spots are a little wider. PD spots may be present to the end of the abdomen and on other segments, all three annul! (or spots) may be present. The longitudinal lateral green line is wider. Femora all brown at base. Abdomen tapering as in male, not much stouter. Abd. apps. somewhat variable in length but longer than 9 -f 10, long oval in form, thin and flat, with rounded apices. Ovipositor reaching middle of 10, about as long as seg. 8. Anx $ 23-27/14-17, $ 24-28/16-18; primary anx 1 and 7 or 8/1 and 5 or 6; pnx $ 15-17/16-20, $ 16-19/17-19 (1$ has 13.14/14/14 and 19 15-7/14-16); cells in triangle $ $ 5-7/3-5, usually with 2 cells on base; cells in supratriangle, $ 9 5-7/4-6; paranal cells in hind wing usually 6; cells in anal loop generally 6-7; cross-veins behind pt. 2-4/2-3. Measurements. Total length $ 86-94, $ 80-93; abd. £56-62, $ 55-63; h. w. $ 53-58, $ 55-62; h. f. $ 11.0-11.5, $ 9.0-12.0; w. hd. $ 11.0, $ 12.5; pt. $ 4.3-5.5/4.5-5.5, $ 4.5-5.8/5.0-5.8. Nymph (pi. 28: 4). A large brown nymph with a mid-dorsal ridge on the posterior segments and little colour-pattern. Head roughly pentagonal, widest at level of median ocellus, eyes not large but very prominent, anterolateral in position; antennae apparently 6-segmented, the last segment as long as 1, 2 and 3 together; lateral margins of head slightly convex, the curve of the posterolateral corners broken by a pair of angular tubercles; hind margin concave. Labial mask extending back nearly to level of anterior surface of mesocoxae; proximal half a little more than half as wide as distal half, the margins nearly straight but in distal half strongly arcuate; ligula gently convex with cleft a little open at margin, densely fringed with scurfy hairs; blades of palpal lobes narrow, not much wider than base of movable hook; distal ends squarely truncate with a rather prominent end-hook. Pronotum with subangular margins, the coxal processes uneven, the anterior being longer and narrower. Wing-cases reaching end of 4. Abdomen slender at base, broadest at 6, being here about equal in width to the head; form lanceolate, semicylindrical on anterior segments, a decided mid-dorsal ridge on 7-10, sharpest on 8 and 9, but not produced into dorsal hooks; lateral spines on 5-9, increasing in size caudad, on 6 reaching about to base of next segment, on 9 about to first fourth of 10, width at base about two-thirds length. Epiproct and paraprocts about equal in length and about two-thirds as long as 9 -f 10; epiprocts with a median ridge; sides in distal two-thirds nearly parallel, truncate at apex,

46

THE ODONATA OF CANADA AND ALASKA

very slightly excavated; cerci nearly two-thirds as long as epiprocts, straight, tapering at acute apices. Colour light brown with dark blotches on the pleura, including a dark median stripe, a broad dark stripe below the mesospiracle, covering lower part of mesepisternum and most of the mesepimeron; metapleura with divided dark blotch; wing-cases dark; legs dark with narrow pale cross-bands at apices of femora and bases and apices of tibiae. Length 48-50, abd. 33-34, w. abd. 10.0-10.5, h. w. 8.5-9.5; w. hd. 10.

Habitat and range. Shady ponds and ditches bordering woods or draining marshes. Fla. to Tex., n. to Me., s. Que., s. Ont., Mich, and Wis.; also Mexico. Distribution in Canada. Que.—St. Hyacinthe, Montreal, Hull. Ont.— Essex, Kent, Elgin, Norfolk, Waterloo, York, Northumberland, Simcoe and Carleton counties, and Muskoka Dist Field notes. This huge dragonfly is not uncommonly seen in southern Ontario, particularly in the counties bordering Lake Erie. But it flies so high, as a rule, that it is usually impossible to catch with a net. Owing to its tendency to enter buildings, it is not infrequently captured and several specimens have been brought to us in this way. Although it is rare north of Toronto, we have taken a few at DeGrassi Point, Lake Simcoe, and have one specimen from the Muskoka District but without further data. E. heros is most often seen in June or early July, but its flight period is remarkably long, our earliest record being dated June 7, 1936 (DeGrassi Point, Lake Simcoe), and our latest September 9, 1948 (Toronto). The last record was of a female which entered a room in the Royal Ontario Museum in the heart of the city. But in Indiana the flight period is more than twice as long as in Ontario, being from about the last third of March to the first third of October (Montgomery, 1947), although it has been recorded only twice after the end of August. The tendency of E. heros to enter buildings may be due to the same impulse which leads them to seek other shady places. The only place where we have found the nymphs of Epiaeschna was a small, shallow and completely shaded pond a few yards inside a wood lot near Scarborough, Ont. Large caddis-worms of the family Limnephilidae were very abundant in this pond. Williamson (1903b) collected nymphs in Tennessee from ditches and marshes. They were associated in the dredging net with a species of chimney-building crayfish. We have twice observed females ovipositing, both times in pools or ditches at the foot of a wooded slope in High Park, Toronto, close to Grenadier Pond. This area was formerly a calla lily swamp. On June 12, 1936, two females of E. heros were flying up and down that part of the ditch which skirts the hill immediately east of Grenadier Pond, where it is partly shaded. They flew somewhat erratically within a few feet of the water, their flight being suggestive of Aeshna umbrosa but without the hovering pauses. At least one of the two females oviposited repeatedly, settling on wet logs lying in the water or on the banks. She never entered the water with her abdomen but operated always at least a few inches above it. While ovi-

FAMILY AESHNIDAE

47

positing she rested in a horizontal position, curving the abdomen into an arch, and inserting her ovipositor into the wet, decayed wood, the anal appendages being held nearly upright Epiaeschna heros is one of the few species of North American dragonflies reported as flying in large swarms. A. H. Mundt (1882) recorded the passage of an immense swarm of this species observed flying towards the southwest over Fairbury, Livingston County, 111. According to this writer the air was literally alive with them; few alighted, and on the following day only a few stragglers remained. Genus Aeshna Fabricius Syst. Ent, p. 424,1775. Type species A. grandis L. This is the dominant genus of the family in the holarctic region and is well represented in South America. There are also a few species in the montane region of Africa (Fraser, 1940), and one in Australia. The species are on the whole of about average size for the family. In our territory both the largest and smallest are boreal forms. In general our species are remarkably uniform in size and colour-pattern, the thorax being brown with a pair of green stripes above and another pair, on each side, of blue, green or yellow stripes. The abdominal spots conform closely to a single pattern with only minor variations (vide Aeshnidae). Most of the spots are usually blue in the males, green of various shades in the females. Heterochromatic females are as a rule commoner than homeochromatic females, but in one species only the latter type is known. The eyes are contiguous for a distance at least as long as the occiput, usually much longer (pi. 4: 3). The frons is of average prominence and bears a well-marked T-spot on the dorsal surface. The thorax is robust with a sharply peaked median carina. The legs are dark brown to black and show no special features. The first two abdominal segments appear inflated, the third decidedly constricted a little before mid-length especially in the male. Segment 10 in the male usually bears a conical dorsal elevation near the base. In the female the sternum of this segment is spinulose or denticulate on the hind margin. The wings (pis. 8-10) are moderately broad, the base of the hind wing of the male and anal loop well developed. The median space is free and the two sectors of the arculus are about equal. The anterior section is somewhat longer. The triangles have typically two basal cells, and the proximal side of the triangle of the hind wing is at least half as long as the distal side. Veins R3 and I R3 both curve forward slightly towards the pterostigma, I R3 being symmetrically forked. The radial supplement is first somewhat diverging from I R3, then converging again beyond the point of bifurcation, the number of rows of cells reaching three or four at the level of widest divergence. Veins R4+5 and MA are at first nearly parallel and separated by

PLATE 6

Male genitalia of Aeshnidae and Gomphidae (AL, anterior lamina; C, collar; D, diverticulum of vesicle; F, flagellum; GP, glans penis; HA, anterior hamule; HP, posterior hamule; M, median segments of penis; PR, prepuce): (1) Aeshna umbrosa, genitalia in situ; (2) Gomphus spicatus, genitalia as seen with walls of genital fossa somewhat pressed outwards, parts of flagella occupy median groove of vesicle; (3) Gomphus lividus, illustrating the short type of penis and the "split-loaf" type of vesicle; (4) Gomphus fraternus, illustrating the long type of penis and the "cleft-pyramidal" vesicle.

FAMILY AESHNEDAE

49

one row of cells, but at some distance beyond the nodus MA bends outwards for a short distance and then runs parallel again with R.4+5 with two rows of cells in the interspace. The median supplement is curved much like Rspl with a similar maximum number of cell rows. The spines of the anterior lamina and the variations of the anterior hamules afford useful taxonomic characters. The spines may be directed downward or curved upward and vary much in length. The anterior hamules usually take the form of small claspers, the hamular processes, usually directed mesad or mesocephalad, being continuous like a collar with the hamular fold near the roof of the genital fossa. In A. juncea and its ally A. subarctica the hamules are peculiar in that each process has become a much longer structure and is quite distinct from the hamular fold, which tends to become vestigial. The nymphs have moderately prominent eyes, whose anteroposterior diameter is usually shorter than the hind margin. The antennae are generally seven-segmented but in two of our species they have only six segments. The posterolateral corners of the head are rounded or rarely bluntly angular. The hind margin is straight or slightly excavate. The folded labium extends back to the middle coxae or rarely to the base of the hind coxae. The palpal lobes are generally squarely truncate with their mesal margins minutely crenulate, but there are several gradations between truncate and hooked extremities. In A. constricta the hook is slender and pointed as in Basiaeschna. The epiproct is a little shorter than the paraprocts and throughout most of its length it is parallel-sided and at the apex deeply bifid. Key to the Species of Aeshna Males 1. Anal triangle 2-celled; spines of anterior lamina directed downward 2 Anal triangle 3-celled; spines of anterior lamina curved upward 11 2. Line of contact of eyes longer than occiput; lateral thoracic stripes generally more than 1 mm. broad, when narrower never sigmoid; hamular processes never with straight, contiguous mesal edges and not concealing the hamular folds (except sometimes in A. subarctica) 3 Line of contact of eyes little or no longer than occiput; lateral thoracic

50

THE ODONATA OF CANADA AND ALASKA

stripes less than 1 mm. broad, the anterior stripe sigmoid or bent twice at alternate angles; hamular processes broad and elevated behind, concealing the hamular folds, their mesal edges long, straight and contiguous 10 3. Hamular processes short (pi. 7: 1), continuous with hamular folds; spines of anterior lamina short and straight 4 Hamular processes long (pi. 7: 2), and narrow, separated from hamular folds, spines of anterior lamina long, tapering to a fine point 9 4. Sup. apps. with a prominent inferior basal tubercle; lateral thoracic stripes broad, not excavated in front; abd. seg. 10 wholly black tuberculifera Sup. apps. without an inferior basal tubercle; lateral thoracic stripes usually excavated in front; abd. seg. 10 with a pair of pale dorsal spots, which are sometimes confluent 5 5. Dorsal thoracic stripes reduced to a pair of small isolated spots (often absent in dried specimens); lateral thoracic stripes reduced, narrow and nearly straight or each divided into 2 spots; vein I R2 arising normally beyond the middle of pt. interrupta Dorsal thoracic stripes complete, expanded at posterior ends; lateral thoracic stripes broad, more or less excavate or sinuate in front; vein I R2 arising normally before the middle of pt. 6 6. Sup. apps. with a low inferior prominence near the base, apices rounded, without a terminal spine and not decurved, dorsal carina somewhat elevated distally, bearing 6-8 well-marked denticles, first lateral thoracic stripe greatly constricted near the middle eremita Sup. apps. without an inferior prominence near the base, apices acute, with a terminal spine, usually slightly decurved, dorsal carina moderately or little elevated, with or without a few small denticles; first lateral thoracic stripe narrowed but not constricted above the middle 7 7. Fronto-clypeal suture with a dark line, a large pale triangular spot in front of the mesopleural suture below; first lateral thoracic stripe curved forward beneath the ante-alar carina; spots between the lateral thoracic stripes very large; lateral edges of sup. apps. nearly straight clepsydra Fronto-clypeal suture without a dark line, with no pale spot in front of the mesopleural suture, first lateral thoracic stripe bent caudad at the upper end; pale spots between the lateral stripes small or absent; lateral edges of sup. apps. moderately elevated with apices decurved 8 8. First lateral thoracic stripe generally blue above, green below, its anterior edge almost rectangularly sinuate, dorsal carina of sup. apps. with a few denticles, hamular processes directed cephalad, subparallel, the apices convergent, not divided into a stout proximal and a slender distal part canadensis First lateral thoracic stripe wholly green, its anterior edge obtusangularly sinuate, dorsal carina of sup. apps. not denticulate; hamular

FAMILY AESHNEDAE

51

processes directed mesoventrad, each consisting of a stout proximal and a slender distal part verticalis 9. Lateral thoracic stripes broad and straight, both lacking a posterior offshoot from the upper end, spines of the anterior lamina curved forward and downward, apices of hamular processes acute and somewhat hooked juncea Lateral thoracic stripes contracted at the middle, the first stripe narrowed above the middle and giving off a slender posterior offshoot from the upper end; spines of the anterior lamina straight and slender, apices of hamular processes rounded subarctica 10. Transverse frontal stripe not produced forward on each side of the T-spot; distance from hind margin of occiput to vertex less than 2 mm.; spines of anterior lamina not longer than the hamular processes, stout, straight and bluntly pointed; MD spots large, irregular or subquadrate septentrionalis Transverse frontal stripe produced forward on each side of T-spot; distance from hind margin of occiput to vertex about 2.5 mm.; spines of anterior lamina longer than the hamular processes, curved downward and tapering to a slender point; MD spots of usual size, triangular sitchensis 11. Abd. seg. 1 without a distinct ventral tubercle, dorsum of seg. 10 smooth; sup. apps. without a well-developed dorsal carina but with an ante-apical hairy tubercle and an ante-apical inferior spine 12 Abd. seg. 1 with a distinct spinulose ventral tubercle; dorsum of seg. 10 with median and submedian tooth-like elevations; sup. apps. with a well-developed superior carina 14 12. Rear of head partly yellowish, a pair of large pale basal spots on ventral surface of segs. 4-6; lateral carina of 7, viewed from below, strongly sinuate or anterior two-fifths; PD spots usually small and green umbrosa Rear of head black; ventral surface of segs. 4r-6 without pale spots; lateral carina of 7 scarcely at all sinuate; PD spots of typical size, blue 13 13. Fronto-clypeal suture with a black line; lateral thoracic stripes nearly straight and equal, surrounded by a black margin; hind wings generally with two paranal cells between A2 and A3, anal loop with three paranal cells palmata Fronto-clypeal suture without a dark line; lateral thoracic stripes widening above the middle, not surrounded by a black margin; hind wings generally with one paranal cell constricta 14. Fronto-clypeal suture with a black line; sup. apps. without an anteapical inferior spine, apices obtuse, dorsal carina not angulate californica Fronto-clypeal suture without black line; sup. apps. with an anteapical inferior spine, the apices acute and decurved, dorsal carina angulate. 15 15. Abdomen (excl. apps.) less than 4 times as long as thorax, seg. 1 with

52

THE ODONATA OF CANADA AND ALASKA

a prominent ventral tubercle; height of dorsal carina above outer margin, in lateral profile, not less than depth of appendage directly beneath it; distance from summit of dorsal carina to apex of appendage greater than one-third of the length of the appendage; western multicolor Abdomen (excl. apps.) not less, generally a little more, than 4 times as long as the thorax; ventral tubercle on seg. 1 little elevated; height of dorsal carina above margin, in profile, generally much less than depth of the appendage directly below it; distance from summit of dorsal carina to apex of appendage about one-third of the length of the appendage; eastern mutata Females 1. Abd. seg. 1 without a distinct ventral tubercle; fork of I R3 decidedly asymmetrical at base; genital valves with distinct lateral carinae 2 Abd. seg. 1 with a distinct ventral tubercle; fork of I RS nearly symmetrical at base; genital valves without distinct lateral carina 14 2. Line of contact of eyes longer than occiput; lateral thoracic stripes generally more than 1 mm. broad, when narrower never sigmoid 3, Line of contact of eyes little or no longer than occiput; lateral thoracic stripes less than 1 mm. broad, the first stripe sigmoid or bent twice at alternate angles 13 3. Basal plate of ovipositor with hind edge straight or slightly arcuate; lateral genital plates present; PL generally confluent with PD (often separate in A. umbrosa) 4 Basal plate of ovipositor bilobate, lateral genital plates absent; PL large but separate from PD (sometimes narrowly connected on 2) 11 4. Styli much shorter than dorsum of 10; anal apps. less than 1.5 mm. wide, more slender in proximal than in distal half, widest beyond the middle; apices generally rounded 5 Styli as long as dorsum of 10 (1-5-2.0 mm.); anal apps. fully as broad in distal as in proximal half, widest before the middle; apices generally acute 12 5. With a black line on fronto-clypeal suture 6 Without a black line on fronto-clypeal suture 9 6. Genital valves 2.0-2.5 mm. long, apices not elevated, bearing a very minute pencil of hairs 7 Genital valves 3.0-3.5 mm. long, apices elevated, without a terminal pencil of hairs; lateral thoracic stripes about 1 mm. broad, straight and not excavated in front palmata 7. Dorsal thoracic stripes absent or represented each by a minute and ill-defined spot; lateral thoracic stripes reduced, often divided into upper and lower spots; I R normally arising beyond middle of pt. interrupta Dorsal thoracic stripes complete or the upper end separated as a distinct spot; lateral thoracic spots more than 1 mm. wide, the first

FAMILY AESHNIDAE

53

stripe deeply excavated in front, I R2 normally arising before middle of pt. 8 8. Without a pale triangular spot in front of mesopleural suture, first lateral thoracic stripe not bent forward at upper end, spots between lateral stripes small eremiia With a large pale triangular spot in front of mesopleural suture; first lateral thoracic stripe bent forward at upper end; spots between lateral stripes very large, often confluent with die stripes clepsydra 9. Lateral thoracic stripes green (rarely blue) not margined with black, the front edge of first stripe sinuate, the second stripe triangular; genital valves 2.0-2.6 mm. long, apices not elevated, bearing a minute pencil of hairs , 10 Lateral thoracic stripes yellow, margined with black or dark brown, straight, the first stripe not sinuate, second stripe not triangular; genital valves 2.7-3.0 mm- long; apices slightly elevated, without a terminal pencil of hair umbrosa 10. First lateral thoracic stripe strongly sinuate in front, narrowed about the middle, its upper end giving off caudad a very narrow offshoot; posterior edge of second stripe generally curved ventral at the upper end; sulcation of ventral surfaces of genital valves not distinctly delimited posteriorly; anal apps. usually 4-6 mm. long canadensis First lateral thoracic stripe more obtusely sinuate in front, its upper end giving off caudad a broad offshoot; posterior edge of second stripe straight; sulcation of ventral surfaces of genital valves terminating more or less abruptly some distance before the apices; anal apps. 5.7-7.0 mm. long verticalis 11. Lateral thoracic stripes broad and straight, not excavated in front, first stripe tapering to upper end, without a distinct posterior offshoot; genital valves with a distinct ventral surface; anal apps. shorter than segs. 8 + 9 ( 5 mm. or less) juncea Lateral thoracic stripes narrower, excavate in front, first stripe obtusangularly bent, narrow above the middle, with a narrow posterior offshoot from the upper end; genital valves without a distinct ventral surface; anal apps. about as long as segs. 8 + 9 (6-7 mm.) subarctica 12. First lateral stripe with front edge nearly straight, tapering dorsad and not giving off a distinct posterior offshoot; second lateral stripe not widened at upper end; genital valves 3.0-3.5 mm. long, apices broad in profile, each bearing a minute pencil of hairs; styli 1-5 mm., spinules on underside of 10 relatively few and coarse tuberculifera First lateral stripe with front edge sinuate, upper end giving off a small posterior offshoot; second lateral stripe widened at upper end; genital valves 4.0-4.5 mm. long, apices slender in profile, without a pencil of hairs; styli nearly 2 mm.; spinules on underside of 10 numerous, minute and close-set constricta 13. Transverse frontal stripe not produced forward on each side of the

54

THE ODONATA OF CANADA AND ALASKA

T-spot; distance from hind margin of occiput to vertex less than 2 mm.; anal apps. about as long as segs. 9 -f- 10; more slender proximally than distally, the apices rounded or broadly and obscurely pointed septentrionalis Transverse frontal stripe produced forward on each side of the T-spot; distance from hind margin of occiput to vertex 2 mm.; anal apps. slightly longer than dorsa of segs. 9 -f- 10; tapering equally at base and apex, the apices bluntly pointed sitchensis 14. With a black line on the fronto-clypeal suture; hind wing less than 40 mm. calif ornica Fronto-clypeal suture without a black line; hind wing more than 40 mm. 15 15. Western; abdomen scarcely more than 4 times as long as thorax; tubercle on first abdominal sternum prominent multicolor Eastern; abdomen about 4.5 times as long as thorax, tubercle on first abdominal sternum low mutata Nymphs 1. Palpal lobes tapering to slender, slightly curved points constricta Palpal lobes truncate or abruptly hooked 2 2. Antennae 6-segmented; lateral spines on 7 to 9 (if present on 6 minute); small northern species 3 Antennae 7-segmented; lateral spines on 6 to 9 4 3. Width of folded labium 70 per cent of length; lateral spines on 7-9 only sitchensis Width of folded labium 58 per cent of length; spines on 6-9 (on 6 minute and not always present) septentrionalis 4. Lateral spines on segs. 5-9 (minute on 5); posterolateral margins of head somewhat obtusangulate eremita Lateral spines on 6-9 only, posterolateral margins of head rounded 5 5. Eyes widest at, or a little behind, the middle (using posterolateral margin of eye as posterior limit of measurement); postocular lateral margins of head convexly curved 6 Eyes widest in front of middle, postocular lateral margins of head nearly straight 14 6. Width of folded labium 78-80 per cent of its length, width at base scarcely more than half the width at the palpal articulation 7 Width of folded labium rarely over 70 per cent of length and not over 75 per cent, width at base variable 8 7. Length 31-33; hind wing case 6.0-6.5; posterior supracoxal process distinctly longer than anterior process; lateral spines of seg. 6 half as long as distance from base of spine to base of seg. 7 californica Length 35-36; hind wing case 7-8; posterior suprocoxal process scarcely longer though broader than anterior process; lateral spines of

FAMILY AESHNIDAE

55

seg. 6 usually less than half as long as distance from base of spine to base of seg. 7 8 8. Lateral spine of seg. 6 vestigial or rarely up to one-fourth as long as distance from base of spine to base of seg. 7; spine of seg. 8 not quite reaching level of base of seg. 9; basal width of lateral spine of 9 equal to about three-fourths of the spine's length; western multicolor Lateral spine of seg. 6 about two-fifths as long as the distance from base of spine to base of seg. 7; spine of 8 projecting beyond level of base of 9; basal width of lateral spine of seg. 9 about half the length of spine; eastern mutata 9. Folded labium slightly shorter than hind femur, not reaching beyond middle coxae, its distal width 60-75 per cent of its length 10 Folded labium slightly longer than hind femora, reaching level of hind coxae, its distal width 55 per cent of its length tuberculifera 10. Femora dark with three pale annuli, abdomen marked with irregular pale blotches on a darker ground colour interrupta Femora uniform; abdomen more or less distinctly striped lengthwise, with a dark median stripe bordered by pale stripes 11 11. Lateral spines on 6 vestigial; longitudinal stripes of abdomen somewhat broken into segmental spots, not always distinct, the dark median stripe no darker than the lateral dark areas 12 Lateral spines on 6 hardly vestigial, though small; longitudinal stripes of abdomen clear-cut, the median stripe usually darker than the lateral dark areas 13 12. Palpal lobes more than 1.5 times as wide as the movable hook at its basal articulation; the distal margin squarely truncate and the outer distal angle little rounded; cerci of male about one-third longer than male projection of epiproct, their apices very slightly incurved; general surface dull juncea Palpal lobes less than 1.5 times as wide as movable hook at its basal articulation, the outer distal angle broadly rounded; cerci of male about one-half longer than the male projection, their apices decidedly incurved; general surface polished subarctica 13. Palpal lobes squarely truncate with outer distal angle very little rounded, the opposing distal margins of the paired lobes parallel verticalis Palpal lobes not squarely truncate, the outer distal angles distinctly rounded, the opposing distal margins of the paired lobes not parallel 14 14. Palpal lobes each terminating in a very abruptly curved and almost truncate hook, dark median stripe deepened about the dorsal puncta canadensis Palpal lobes each terminating in a broadly curved hook; dark median stripe of abdomen not deepened about the dorsal puncta clepsydra 15. Width of folded labium two-thirds of the length, anterior and posterior supracoxal processes about equal in length and width palmata

PLATE 7

Male and female genitalia: (1) Aeshna eremita, male, anterior lamina and anterior hamules—the hamular processes are short and continuous with the hamular folds; (2) Aeshna júncea, male, anterior lamina and anterior hamules—the hamular processes are long, hooked and separate from the hamular folds; ( 3 ) Aeshna canadensis, female terminalia, ventral view; (4) Aeshna canadensis, female terminalia, lateral view; (5) Gomphus spicatus, female terminalia, ventral view; (6) Cordulegaster maculatus, female terminalia, lateral view.

FAMILY AESHNIDAE

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Width of folded labium three-fifths of its length; posterior supracoxal process decidedly wider than anterior process umbrosa Aeshna eremita Scudder. (PL 7: 1; pi. 13: 1; pi. 15: 1, 2; pi. 20: 1; pi. 23: 1; pi. 26: 1) Aeschna eremita Scudder, Proc. Boston Soc. Nat. Hist., 10: 213,1866. Aeshna eremita Walker, Can. Ent, 40: 383,1908. Aeschna hudsonica Selys, Ent. M. Mag., p. 242,1875. Aeschna clepsydra Calvert, Trans. Amer. Ent. Soc., 20: 248 (1893). A large robust species of wide distribution in the north, the males bluespotted, the females usually green. Male. Labium pale to lemon yellow; lateral lobes greenish blue; face pale to yellowish green with a black or brown boundary line; labium bordered with black or brown; fronto-clypeal suture with a black line; postfrons with a T-spot; vertex yellow in front; occiput yellow, black in front; rear of head black. Pterothorax dull grayish brown, grayish below; median carina and ante-alar carina black; dorsal stripes bluish green, 4r-5 mm. long, upper ends somewhat widened, and often separated as distinct spots; lateral stripes chiefly blue, often partly green below, anterior stripe broad and rounded below, deeply constricted just above the middle by an anterior incision, widening again a little above with a short posterior offshoot, which is sometimes a separate spot. Posterior stripe triangular with a shallow excavation in front; legs dark brown, front pair with a pale greenish streak along anterior surface. Abdomen brown to black with a typical pattern of blue spots, as follows: seg. 1 brown, dorsal spot blue, lateral spot bluish or green; 2 brown, AML blue, sometimes green in front, rhomboid, confluent above with MD; PL and PD united, forming a broad transverse stripe; 3-10 brownish black, spots rather large, azure blue except MD which is dull yellow; AL on 3-8, on 3 a large subtriangular area on each side, separated by a dorsal brown stripe; on 4-8 smaller and decreasing in size caudad, becoming minute on 8; ML on 3-8, small quaduate spots immediately behind AL, confluent with MD on 3, transversely elongate triangular; PD large posterodorsal paired spots, extending to seg. 10 inclusive. On 10 they are either separate or connate; PL on 3-9, straight, narrowly connected behind with PD on all the segments. Abdomen widening from the constriction at seg. 3 to the posterior end of 4; seg. 1 bearing numerous minute spinules on the posterior half, auricles with 4 teeth; spines of ant. lamina straight, acute, directed downward and laterocaudad; hamular processes short and thick, with apices produced into a papilliform process, larger than that of A. interrupta but shorter than that of A. verticalis. Sup. apps. about one-sixth shorter than 9 -f- 10, widening gradually from base to about the middle where the width is about one-fifth of the length, thence narrowing very slightly to broadly rounded apices

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THE ODONATA OF CANADA AND ALASKA

which only rarely bear a minute terminal tooth; mesal margin only very slightly sinuate; dorsal carina ratner strongly elevated in the distal three-fifths, bearing 6-8 well marked denticles, in profile the basal fourth appears thickened by the presence of a large but low ventral tubercle; inner margin beyond the middle deflected, forming a fairly prominent inferior carina. This carina together with the elevated superior carina above it gives the appendage the appearance of being rather strongly bent upwards in its apical third. Int. app. slightly shorter than sup. apps., triangular with apex blunt and rounded; in profile with the usual upward curvature. Wings shorter than abdomen, hyaline; costal veins brownish ochraceous; pt. smoky brown above, ochre yellow below; membranule of hind wing smoky gray. Female generally heterochromatic, but a complete range of variation occurs from blue to yellow-green. Heterochromatic females often have flavescent wings. Dorsal thoracic stripes reduced and divided into a larger anterior spot and a short, wide posterior spot. Genital valves about as long as seg. 9, the lateral carinae subparallel distally, hearing a minute pencil of hairs. Styli .75 mm. long; basal plate of ovipositor with jjosterior margin straight; spiny area on ventral surface of 10 rather large with numerous c oarse spines, anal apps. variable in length with locality, generally about as long as 8 -f- 9, oblanceolate, greatest width a little beyond middle one-fifth to two-sevenths of length, apices broadly rounded or subangulate. Anx 15-11/11-15, pnx 11-16/13-17; usually 2 paranal cells between A2 and A3; usually 3 rows of cells between forks of I R3 at the level of distal end of pt; 4 to 5 rows of cells between I R2 and Rspl. Measurements. Total length $ 72-79, $ 66-78; abd. $ 50.0-58.5, $ 45.0-52.0; h. w. $ 45-52, $ 41.0-49.5; h. f. $ 9.0-10.8, $ 9.0-10.5; w. hd. 3 9-10, 9 8.8-10; pt. $ 3.3-3.8/3.5-4.0, $ 4.0-4.3/4.0-4.5. Nymph (pi. 29: 1; pi. 30: 1; pi. 33: 1). Head widest a little behind middle of eyes; lateral margins nearly straight, posterolateral corners obtusangulate, sometimes a little rounded, posterior margin nearly straight; antennae 7-jointed; distal width of folded labium 70 per cent of length; proximal width of prementum 61 per cent of distal width; lateral margin of prementum strongly arcuate in the distal 36 per cent of its length; ligula nearly two-fifths as wide as distal width of labium; palpal lobes squarely truncate, their distal margins parallel, distolateral angles very little rounded, distomesal angles with a small tooth, supracoxal processes about equal in length and width, acute and somewhat divergent; lateral spines on segs. 5 to 9, very small on 5, on 8 reaching posterior margin of the segment, on 9 to middle of 10. Ovipositor not quite reaching the posterior margins of 9. Head behind eyes with an oblique brownish patch on each side and a pale marginal stripe extending from eyes to hind edge of pronotum or further. Femora brownish with three paler annuli, tibiae and tarsi almost uniform. Dorsum of abdomen with a paired series of pale blotches, each enclosing a darker median blotch, the pale blotches confluent throughout the first 5 or 6 segments but breaking up into separate pairs of spots on the remaining segments; other pale dorsolateral and lateral blotches between the dorsal series- and the lateral margin as shown in plate 29: 1, puncta dark, the dorsolateral series enclosed in pale blotches, lateral spines whitish, black tipped. Length 41.0-47.7; abd. 28.0-32.5; w. abd. 8.1-9.5; h. w. 8.5-11.0; h. f. 7.5-8.7; w. hd. 8.0-9.5.

Habitat and range. Marsh-bordered lakes, ponds and slow streams; Nfld. and Labr. to Hudson's Bay, northern Mackenzie and Alaska, s. to Mass., N.H., Vt, n. N.Y., s. Ont, Mich., Wis., Man., Wyo., Utah and B.C. Distribution in Canada and Alaska. Nfld.—White Bay, Bay of Islands; Grand Lake; Hell Hole Pond; Tor's Cove; Gander. Labr.—Hopedale. N.S.— Annapolis Co., Asby Bay, C.B. N.B.—Nelson. Que.—Magdalen Is.; Fort

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George, Rupert House and Pt. Comfort, James Bay; Atik River, 45 mi. from mouth; Natashquan and Bradore Bay; Godbout, Pointe des Monts and Trinity Bay, n. shore of lower St. Lawrence; Chicoutimi; near Lake Temiscouata; Cascapedia; Montreal; Aylmer; Wakefield, and other statioris in the Gatineau Valley; Mont Tremblant Park. On*.—Peel, York, Dufferin and Simcoe counties; Muskoka, Parry Sound, Nipissing, Algoma, Thunder Bay, Cochrane, Kenora and Rainy River districts. Man.—Husavick; Treesbank; Onah; The Pas; mile 214, Hudson Bay Ry.; Lake Atikameg; Blue Lakes; Gillam. Sask.—Prince Albert; Waskesiu; Stony Lake; Reindeer Lake; Wapus River; La Ronge. Alta.—Fort Smith; Athabasca Landing; Tazin Lake; Healy Creek; Bow Valley; Red Deer. B.C.-Atlin; Fort Nelson; Massett dist., Q.C.Is.; Forbes Landing, Courtenay and Wellington, Vancouver L; Vancouver, Drisy Lake, Garibaldi Dist.; Harrison Bay, numerous localities in the interior from Princeton to Canal Flats, n. to Prince George, including Aspen Grove, Vernon, Kaslo, Kamloops and Salmon Arm; in die Columbia River trench, and Edgewater. N.W.T.—Eskimo Point, Keewatin Dist.; Mackenzie Dist.; Fort Rae; Fort Simpson; Great Slave Lake (Fort Resolution, Gros Cap and Yellowknife); Norman Wells; Great Bear Lake (Fort Radium, Conjuror Bay); Reindeer Depot; Aklavik. Ywfcon T.—Whitehorse, Dawson, Squaaga. AZosfca—Bethel, Kuskokwim River; Admiral L; Anchorage, Chitina, Gulkana, Palmer. Variation. This species is very uniform throughout its immense range. Our most northerly specimen, a female from Aklavik, is also the smallest, measuring 66 mm. in total length. As a rule the northern specimens are among the largest. Field notes. This large Aeshna is widely distributed ecologically as well as geographically. It inhabits the forested regions of Canada almost everywhere, except in the extreme south of Ontario. The nymphs develop in weedy bays of lakes or slow streams and ponds of various types. We have observed the adults patrolling the margins of small lakes and ponds, where there was no extensive marsh; and over the small ponds and railway tracks in a cutting through a northern black spruce swamp. We have also taken them with A. interrupta flying over a waterfall on the Godbout River, Quebec, and along the edge of the woods on a neighbouring beach. A. eremita is everywhere an early species to appear in the adult stage. In 1952 we found an exuvia near Limberlost, Ont., on June 19 and on the same day we saw an adult male which settled near enough to us to be easily identified. On the twenty-first we saw other individuals skirting the margins of two other neighbouring lakes, which from their size were doubtless also eremita. In the far north emergence commences at an equally early, if not earlier, date, for we have examined six males and three females from Fort Smith, N.W.T. (60°N) dated June 11-29,1950. Three males were taken on June 11, a week earlier than the earliest date we had previously reported it. Most of our records of this species are dated July, but many specimens

60

THE ODONATA OF CANADA AND ALASKA

were taken in August and a few in September. Although the main emergence is early, it continues sporadically over a long period. We found a female emerging in August (exact date lost) at Go Home Bay, Georgian Bay, Ont., and we have found full-grown nymphs in the Nipigon River in August, which lived in the laboratory until the following January without feeding, having apparently entered a diapause. It is evident that the nymphs usually reach the final stage in the summer before the year they are due to emerge. A few individuals may possibly reach this final stage earlier in the season and emerge in late summer without passing through the diapause. The latest dates on which we have recorded A. eremita are September 25, 1891, and September 15, 1906, both from Toronto, where this species is no longer found. A. eremita flies chiefly during hours of sunshine, but is sometimes found flying after sundown, in company with other species (Williamson, 1907a). We have observed the same habit. Oviposition is performed on various floating or emergent plants, for example, Sparganium (Walker, 1912), Nuphar and Potamogeton (Robert, 1944). The first female we observed was clinging to the blade of a bur-reed with about half of the abdomen immersed. The abdomen was thrust against the stem every two or three seconds and was gradually lowered until wholly under water. The punctures made by the ovipositor were arranged in somewhat irregular oblique rows and the eggs placed obliquely in the plant tissue. We have also observed eremita, while supported on a collection of dead floating reeds, among a thick growth of living ones, thrust her ovipositor, seemingly at random, into any piece of plant tissue she could reach. Such operations do not last long and appear to be merely exploratory. Aeshna interrupta Walker. (PL 15: 2, 3; pi. 23: 2) Aeshna interrupta Walker, Can. Ent, 40: 381, 387, 1908; Univ. Toronto Stud., Biol. Ser., no. 11, p. 100,1912. Aeschna propinqua Scudder, Proc. Boston Soc. Nat. Hist., 10: 215, 1886 [in part]. Aeschna clepsydra Calvert, Ent. News, 5: 11,1894. Aeschna *W Williamson, Ohio Nat, 7: 146,1907. An average-sized Aeshna with dorsal thoracic stripes much reduced, the colour-pattern otherwise typical; widely distributed in Canada and very abundant in the Prairie Provinces. Male. Labium pale yellowish obscured with brown; lateral lobes bluish or leaden; face pale green, with a black line along the lateral margins, on the labrum, above and below, and on the fronto-clypeal suture; postfrons paler than face behind the thick T-spot; vertex greenish yellow, broadly margined with black; occiput clear light yellow, rear of head black. Pterothorax dull yellowish or grayish brown, moderately hairy; dorsal stripes reduced to narrow green spots about 2.0-2.5 mm. long; lateral stripes also reduced, each represented either by a pair of separate or narrowly connected spots, or by a

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61

linear streak, which may be entire or broken, blue above, yellowish green below. Femora reddish brown, black beneath, the fore pair often with a pale streak on the anterior surface; tibiae and tarsi black. Wings hyaline, costal veins pale brownish yellow; pt. dark smoky brown above, pale greenish brown beneath; membranule smoky brown with the basal fifth or more white. Abdomen with the typical blue-spotted pattern; seg. 1 brown with a blue dorsal spot and a green lateral one, 10 with dorsal spots small and pale green, the spots on the remaining segments blue except MD, whch is pale greenish. Sup. apps. generally a little shorter than 9 + 10, of the usual paddle shape, characterized in particular by rounded apices sometimes armed with a minute projecting tooth but not decurved, the dorsal carina obsolete in the middle fourth, gradually elevated distally, where it bears 2-6 minute denticles; outer edge in lateral view slightly curved ard, inner (lower) edge forming a low, obtusangular, inferior carina; inf. app. it three-fifths as long as sup. apps., and twice as long as the basal width, triangular with bluntly rounded apex. Spines of ant. lamina very short and blunt, their apices concealed in lateral view; hamular processes directed inferomesad, short and broad, their mesal margins rounded, terminating in a minute tubercle; hamular folds continuous with the processes, ear-like as in eremita.

r

Female marked similarly to the male, with the usual somewhat larger size of the pale areas, which are usually green with the lateral spots bluish, although completely heterochromatic females with the pale markings all green are not uncommon. Purely homoeochromatic females are rare. Genital valves extending caudad about as far as the posterodorsal margin of 9, apices not elevated; lateral carinae percurrent, prominent, in profile irregularly arched, viewed from below divergent in the proximal third; styli slightly more than half as long as dorsum of 10 (.7 mm.); basal plate with hind eage straight, lateral plates distinct, anal apps. varying in length, usually from somewhat shorter to somewhat longer than segs. 8 + 9, oblanceolate, widest at about three-fifths to two-thirds of the length from base, the width being about one-fifth of the length, apices rounded; only rarely with a minute terminal tooth. Anx 3 16-22/12-14, $ 17-22/11-14; pnx $ 10-12/11-15, $9-13/11-14; h. w. with 5-6(7) paranal cells, anal triangle 2-celled; I R3 forking at level of one or two costal cells before pt. or behind pt. near proximal end, with 3 rows of cells between the forks opposite distal end of pt., and 4 rows across widest part of Rspl loop; cells in triangle typically 5/4; cells in Spt 3-5/3(4); cross-veins under pt. £ 2-3/2-4, $ 3-1/2-3. Measurements. See under subspecies. Nymph (pi. 30: 2; pi. 33: 6). Very similar to A. eremita but a little smaller; eyes as in eremita; lateral margins of head slightly convex, the posterolateral corners broadly rounded, posterior margin slightly concave. Folded labium a little narrower than in eremita, the distal width being 65 per cent of the length, as compared with 70 in eremita; width of prementum at base 58 per cent of distal width, the convexity of the lateral margin in the distal three-eights of its length less pronounced than in eremita. Palpal lobes squarely truncate, with the distolateral angle scarcely rounded. The distomesal angle with a minute tooth. Supracoxal processes moderately prominent, the anterior process slightly longer and more slender than the posterior. Abdomen shaped as in eremita, widest at 6; lateral spines on 6-9, not at all divergent, extending on 7 as far back as the rear margin of this segment; on 8 a little beyond the margin and on 9 as far as proximal three-fifths of 10. Ovipositor not quite reaching the apical margin of 9, genital valves three times as long as wide. Colour-pattern very similar to that of eremita; head behind eyes with a dark submarginal blotch on each side and a pale lateral margin extending from eyes to rear edge of pronotum. Femora brownish with three pale annuli, tibiae and tarsi almost concolorous. Abdomen brown with pale mottlings as described for eremita, but the dark

62

THE ODONATA OF CANADA AND ALASKA

mid-dorsal stripe usually broken into pairs of spots by a series of median pale spots, the general appearance being a mottled rather than a striped pattern. Length 39.0-41.5; abd. 25-27; w. abd. 7.3-8.0; h. w. 8.0-8.5; h. f. 6.5-7.2; w. hd. 8.0-8.3. The nymphs of the various subspecies are indistinguishable.

Habitat and range. Shallow marshy bays with abundant emergent vegetation; also ponds and slow streams. Nfld. to Mackenzie, Yukon T. and Alaska, s. to N.S., N.B., Me., N.H., Vt., n. N.Y., s. Ont, Mich., Minn, and N. Dak., and s. along mts. to N. Mex., Utah, Nev. and Calif. A. interrupta is divided into several subspecies or geographical races, of which the following have been commonly recognized in Canada and Alaska. 1, Lateral thoracic stripes divided into two roundish spots, an upper and a lower, spots of the first stripe in the female often not quite separated; anal apps. of female usually a little longer than segs. 8 + 9, their apices broadly rounded interrupta Lateral thoracic stripes usually entire, if divided more or less linear, anal apps. of female usually a little shorter than segs. 8 + 9, their apices less broadly rounded 2 2. Sup. apps. of male with a ventro-mesal basal tubercle; lateral thoracic stripes .75 to 1 mm. wide interna Sup. apps. of male without a basal tubercle, lateral thoracic stripes usually .5 mm. to .75 mm. wide at lower end lineata We have decided to drop the name nevadensis from the Canadian list, since it shows no constant differences from A. interrupta lineata. Our original description was based on eight specimens all from Reno, Nevada, and seemed distinct enough to deserve subspecific rank. But since Kennedy collected nevadensis in numbers in 1915 and figured it fully in his paper of 1917, it seems to be indistinguishable from lineata of the prairies. At any rate it is unrecognizable as a subspecies in Canada. The Subspecies of Aeshna interrupta The status of these subspecies is not yet clear. East of the Rocky Mountains there are two well-defined geographical races, interrupta which, broadly speaking, inhabits the forested region of Canada east of the Great Plains and lineata, which .occupies the Prairie Provinces to the Rocky Mountains and northward to the subarctic forests of Mackenzie, Yukon Territory and Alaska. Intergrading of these races is known only from the region of Favourable Lake, Ont., near the Manitoba boundary, but intermediate specimens are commoner there than either of the typical races. From the Canadian Rockies westward A. interrupta is not distinctly divided into subspecies. In the Rocky Mountains of Alberta and British Columbia and northward to the Yukon Territory and Alaska lineata continues as in the Plains. In the Selkirk range and Kootenay Valley lineata passes into interna, but the characters of this race are less pronounced than

FAMILY AESHNIDAE

63

they are farther south. Interna is a mountain form ranging southward through Idaho, eastern Washington and Oregon into Utah, Colorado and New Mexico. Westward to the Pacific Coast in British Columbia the lateral thoracic stripes become divided and even widened as in the east, with the result that the coastal form is not sufficiently distinct from the eastern interrupta to be given another name. Typical interrupta is somewhat larger and the anal appendages of the female longer than in any of the western forms, but in the cooler parts of the range, such as Newfoundland, these appendages are quite as short as in any of the western races. This form has been reported from Alaska by Mrs. Gloyd (1938) as interrupta, and, pending further study of the species from its entire range, it appears best to leave it under that name. It was recorded as race interrupta from Inverness, B.C., by the writer in 1912. Aeshna interrupta interrupta Walker. (PL 15: 2; pi. 20: 3, 4) Aeshna interrupta interrupta Walker, Univ. Toronto Stud., Biol. Ser., no. 11, p. 103,1912. This subspecies is typically a little larger than the other forms. The black line on the fronto-clypeal suture and usually the T-spot are heavier; the hair on the thorax is somewhat darker and, in the male, the lateral thoracic stripes are constantly divided into two spots, although in the female, the first stripe is often not quite divided, being somewhat hourglass-shaped. In specimens from the extreme east (Newfoundland and the Magdalen Is., Que.) both stripes may be wide and only constricted, but on the mainland from Nova Scotia to Lake Superior there is very little variation in this subspecies. Sup. apps. of male are shown in pi. 20: 3, 4. The lateral margins are only slightly convex, the mesal margins distinctly sinuate, the greatest width is at about the proximal two-fifths, being about twice the width at base, apices broadly rounded and sometimes armed with a minute projecting spine. Dorsal carina indistinct on proximal fourth, gradually elevated distally, where it bears 2-6 minute denticles. The range of colour in the female is complete, but the blue form is rare. Most females are intermediate in colour-pattern, the pale markings being mostly greenish yellow but with the lateral spots somewhat bluish. Examples of extreme heterochromatism, with the markings of the thorax and abdomen all yellow-green, are not uncommon. The most striking structural feature of the female as a rule is the length of the anal apps. As with all northern species of Aeshna these apps. vary in length with locality, the differences being apparently correlated with summer temperature, the shortest apps. being found in regions of low temperature (Walker, 1912). But in general the appendages of this subspecies are longer than those of the other subspecies, ranging from 6.5 to 7.5 mm. Measurements. Total length $ 66-74, $ 66-78; abd. £ 41.5-51.0, $ 41.0-54.5; h. w. $ 43.0-47.5, $ 41-50; h. f. $ $ 8.5-9.0, pt. $ 3.3-4.0/3.4-4.0, $ 4.0-4.4/3.7-4.5. Variation. Females from Newfoundland and the Magdalen Islands, Quebec, differ from those of the Continent from Nova Scotia to western Ontario in the shorter and deeper third abdominal segment and in the coalescence of the spots on the sides of the thorax. The anal apps. are shorter, more slender and more acute than in those from the Continent. As only very few specimens have been seen from this region we do not know whether the differences from the continental form are constant or not, nor whether they should be considered as indicative of a separate subspecies. The largest specimens we have seen are from Ogoki, Ontario, at the junction of the Ogoki River with the Albany River at 51°N, 84°W.

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THE ODONATA OF CANADA AND ALASKA

Habitat and range. Shallow, marsh-bordered bays, boggy or marshy ponds and slow streams. Nfld. to Godbout, Que. (49°2(XN), Moosonee (52°N) and Favourable Lake (53°N), Ont., s. to Mass., n. N.Y., s. Ont., and Mich. Also on die Pacific Coast from s. B.C. to Alaska. Distribution in Canada and Alaska. Nfld.—Grand Lake; Bay of Islands; Avalon Peninsula. N.S.-Truro; Aspy Bay, C.B. N.B.-Sackville; South Nelson. Que.—Aylmer; Wakefield and other stations in the Gatineau Valley; Cascapedia; Mont Tremblant Park; Chicoutimi; Malamek River, Saguinay Co.; Godbout; Trinity Bay; La Ferme, Abitibi Co.; Magdalen Is. Ont.— Peel, Ontario, Simcoe and Renfrew counties; Muskoka, Haliburton, Parry Sound, Nipissing, Timiskaming, Sudbury, Algoma, Thunder Bay, Cochrane and Kenora (Patricia section) districts. B.C.—Vancouver I. (Departure Bay, Forbes Landing); Vancouver; Inverness. Alaska—Admiralty I.; Ketchikan. Field notes. This subspecies breeds in many types of ponds and lakes in the boreal and northern parts of the mixed forests. We have found the exuviae on cat-tails in a trout pond, on various emergent plants in shallow, marshy bogs, e.g., on the Nipigon River, and on branches of sweet gale (Myrica gale L.) growing around the margins of bog ponds. We have found the adults flying over the same types of habitats and also over shallow ponds with a firm bottom, supporting a close stand of Equisetum fluviatile and Typha; and in the Lake Abitibi region, we have found them coursing over the small ponds and ditches along a railway cutting through a black spruce swamp. Robert (1944) notes that they show a preference for bog lakes, when the water is dark. He also observes that while the males follow the contours of the shore the females are engaged in oviposition, supporting themselves on twigs or on fallen tree trunks along the water's edge. They also oviposit on standing aquatic plants. When flying over open marshes in company with other species of Aeshna, such as eremita, canadensis or juncea, they may be easily recognized while hovering, by the dark appearance of the thorax, due to the reduction of the pale stripes. At Godbout they were seen in great numbers with A. eremita, flying in the valley of the Godbout River, over the beach, along the edges of woods or even over a waterfall. Evening flight of interrupta until after dusk has been mentioned by Williamson (1907). Many shallow pools, following heavy showers were left in the yard of a shingle mill and after sundown, when the rain had ceased, dragonflies began to appear over these pools. They were all aeshnids, A. interrupta, eremita and canadensis, and Boyeria vinosa, all males. They were still flying when the darkness rendered them almost invisible. A. interrupta emerges later than either eremita or canadensis. The earliest date on which we have found an exuvia is July 2, 1942, at Hickory Lake, Muskoka, Ont., but we have one earlier record from the Magdalen Islands, Que., namely, June 30. This is surprising as the summer season is much later in the extreme east than in Ontario. Generally, in Ontario, the tenerals begin to appear about the middle of July or during the second week. Most

FAMILY AESHNIDAE

65

of our captures were made during late July and August. They fly well into September, however, although we have only rarely had the opportunity of observing them after the end of August. We have one record, however, of watching a very worn female of the yellow-green type ovipositing. on October 1, 1950. This was in a shallow, cow-trodden pond near Snelgrove, Ontario. The dragonfly was almost hidden in a dense stand of subaquatic plants, chiefly a species of manna grass (Glyceria borealis). It was on this grass that the insect was supported and on the culm of which it was ovipositing. The entire range of dates for the flight period of A. interrupta interrupta in Ontario is July 2 to October 1, but it is probably too long a period for the majority of seasons. Aeshna interrupta lineata Walker. (PL 15: 3; pi. 20: 5, 6, 7, 8 ("nevadensis"), 9) Aeshna lineata Walker, Can. Ent, 40: 382,388,450,1908. Aeshna interrupta lineata, Walker, Univ. Toronto Stud., Biol. Ser., no. 11, p. 112. This is a slightly smaller insect than A. i. interrupta, but with a relatively somewhat more robust thorax. The black line bordering the face on each side and the frontoclypeal line are slightly narrower. The thorax appears a little paler owing to the longer and paler hairs that clothe it. The dorsal stripes are even more reduced or may be absent. The lateral stripes are linear, nearly straight, greenish yellow below, more or less bluish or blue above, the first stripe .5 mm. or less wide at the lower end and tapering above to a fine streak; the second stripe still narrower below, somewhat more oblique and backwardly curved, often interrupted below the middle. The abdominal pattern is nearly identical with that of subspecies interrupta, but the blue spots are a little larger. Sup. apps. barely shorter than 9 + 10> differing little from those of interrupta but usually widening gradually from base to three-fifths of the length, the width here being a little less and the rounded apices usually smaller than in interrupta. The curve of the lateral margins is stronger ana the mesal margin less sinuate, the appendages in profile more strongly curved upward. The inf. app. is similar to that of interrupta but is sometimes two-thirds as long as sup. apps. The differences in form exhibited by the females of lineata and interrupta correspond to those of the males. The anal apps. are usually shorter than 8 + 9, the apices less broadly rounded than in interrupta, often with a slightly indicated apical tooth. The usual wide range of colour is found in the females of this subspecies as in the eastern form. Measurements. Total length $ 66-72, 9- 62-70; abd. $ 47-51, $ 43-49; h. w. 3 42-46, $ 43-46; h. f. $ 8.0-9.5, $ 8.0-8.5; w. hd. $ 9.5-9.8; $ 9.0-9.5; pt. $ 3.5-4.2/3.6-4.1, $ 3.5-4.5/4.0-4.4.

Habitat and range. Prairie sloughs and other ponds on both prairie and forested terrain. Kenora Dist. of Ont. through n. Man. and N.W.T. to Y.T. and Alaska, s. to Minn, and N. Dak., and, as "nevadensis" to Nev. and central Calif.; s. Sask., s. Alta. and B.C., w. to the Gold and Cascade Ranges. Also recorded from L. Abitibi, n. Ont., near Quebec boundary line. The known northern boundary of its range is as follows: Favourable Lake, Ont.

DO

TOE

ODONATA OF CANADA AND ALASKA

(53°N), Pikwitonei, Man. (55°35'); Fort Chipewyan, Lake Athabasca, Alta. (61°N); Norman Wells, Mackenzie, N.W.T. (65°N); Dawson, Y.T. (64°N); Palmer, Alaska (61°3(y). Nymph. See under interrupta p. 61. Distribution in Canada. Out.—Cochrane Dist, Lowbush, Lake Abitibi; Kenora Dist., Malachi, Favourable Lake region in Patricia section. Man.— Treesbank, Winnipeg, Victoria Beach and Winnipeg Beach, Lake Winnipeg; Stockton; Husavick; Westbourne; Riding Mountain Nat. Park; Swan River; The Pas; Lake Atikameg; Pitwitonei; Blue Lakes. Sosfc.—Carlton; Regina; Moose Jaw; Swift Current; Maple Creek; Madison; Snipe River; Hamton; Humboldt; Lac Vert; Vonda; Prince Albert; Waskesiu Lake; Polwarth; Stony Lake; La Ronge. Alta.—Red Deer; Stettler; Waterton Lake; Banff; Jasper Park; Fort Chipewyan, Lake Athabasca; Fort Smith. B.C.—Yellowhe:ad Pass, McBride; Tete Jaune; Mt. Robson, Fort Nelson. N.W.T.-Mackenzie: Fort Simpson; Fort Resolution, Gros Cap and other stations on Great Slave Lake; Buffalo River; Seven Mile Creek; Norman Wells; Conjuror Bay, Great Bear Lake. Yukon T.-Dawson (13(Xy); Snag; Mayo. AlaskaChitina; Palmer; new records: Harvie, July 19-28; Haine, July 19-28. Field notes. This is the dominant Aeshna of the Great Plains in Canada, far outnumbering all the other species taken together. It ranges also northward beyond the prairies; it is abundant at The Pas, Man., and fairly common about Great Slave Lake and even farther north in the Mackenzie Valley. Eastward it appears in the Lake of the Woods region in typical form but integrades with subspecies interrupta farther north in the Favourable Lake district, near the Manitoba boundary. The capture of two females of typical lineata at Lowbush, Lake Abitibi, however, suggests that the two subspecies may not interbreed very freely, since all other specimens taken from the Lake Abitibi region and northward to Attawapiskat Lake and Ogoki, Ont., are typical interrupta. Although numerous specimens of lineata have been taken by various collectors and we have collected many ourselves, very little is known of its habits in Canada. It breeds in a variety of quiet waters, such as shallow sloughs, bog ponds and marsh-bordered lakes, both in prairies and forests. When we visited Victoria Beach, Lake Winnipeg, during the last week of June, 1931, it was just becoming common. At The Pas, in early July of the same year, it was already abundant in clearings along the North Saskatchewan River, and over the beach and road hundreds were in flight on July 9. Many were also seen flying up and down a freshly dug ditch containing running water. This was along a railway cutting through a sprucetamarack swamp. The breeding places in the vicinity of The Pas, however, are doubtless neither the river nor the bog ditches but the numerous marshbordered sloughs and small lakes in this region. They were surrounded by a zone of tall reed-grass (Phragmites communis) and were extremely difficult to approach. We have noted (1927) that in the vicinity of Banff, Alta.,

FAMILY AESHNIDAE

67

ineata was taken in 1921, flying over a large marshy pond in the Bow /alley, but did not appear at the small sloughs along the railway track, where A. juncea was abundant. The flight period of lineata apparently oegins earlier than that of interrupta, even in the high north. The earliest late among our records is June 3, about a month before our earliest d£te for interrupta and even at Fort Smith (60°N) we have records from June 19 and 27. They appear to be everywhere most abundant in July and August and have been taken as late as September 6. Kennedy (1917) found this form, recorded as nevadensis, in central California at various altitudes from 4,500 to 7,000 feet. At this last elevation it w^s found "in its greatest numbers between McKinley Creek and the Rubicon River." Here it dominated all other dragonfly life. Three of the lakes are covered with yellow pond lilies and fringed with sedges while numerous clumps of gray willows dot their shores. These lakes swarm with insect life and their unusual warmth appears to be due to their shallowness, the black peaty mud covering the bottom, and the constant clear weather in this region during the summer months. But the air was so cool that Aeshna was easily taken on the wing. . .. This species emerges from these lakes in immense numbers. I have never seen Aeshna exuviae so numerous. At the lake about which I did most of my collecting there was a zone of sedges 5 to 25 feet wide along the shore. The majority of the sedge stems were riddled with eggs, and the exuviae hung frequently two or three deep on the prominent ones. I picked nearly a quart from an area about 15 feet square. While adults swarm over these ponds* they are not one-tenth as abundant as the exuviae, a fact explained by the wandering proclivities of both males and females. (Kennedy, 1917)

Kennedy further states that, unlike most species of Aeshna which he had observed, "nevadensis" emerges during the day instead of the night, a change of habit which is associated with the low air temperature of these lakes at night, which approaches freezing point. Oviposition was observed as early as 10 A.M. and was usually performed on the stems of Carex below the water surface. While the females were thus engaged, the males were circling the borders of the lakes, catching insects and watching for females, which were usually captured while ovipositing. For further information on the habits of "nevadensis" (=lineata), which probably applies in general to the species interrupta, as a whole, see Kennedy (1917). Aeshna interrupta interna Walker. (PL 15: 4; pi. 20; 10,11) Aeshna interna Walker, Can. Ent., 40: 381, 388,450,1908. Aeshna interrupta interna Walker, Univ. Toronto Stud., Biol. Ser., no. 11, p. 116,1912. In its typical form this subspecies differs from lineata in the somewhat greater development of the pale areas of the thorax and abdomen and in the form of the superior appendages of the male.

68

THE ODONATA OF CANADA AND ALASKA

The first lateral thoracic stripe is .75 to 1.00 mm. wide below, narrowing to about half that width a little above the middle, then remaining equal or widening slightly toward the upper end. The second stripe is of similar width below, curving slightly caudad, sometimes slightly constricted at the middle and widening a little in the upper half. The abdominal pattern is as in lineata but with the spots averaging somewhat larger, especially MD, which is also more or less quadrate in the male, though triangular in the female. The sup. apps. of the male, viewed from above, show the mesal margins to be more decidedly sinuate than in lineata, whereas in profile the inferior carina, which they form distally, is somewhat obtusangular rather than curved, as in lineata. Proximad of the carina the sup. apps. are slightly undulate in outline. The most useful character in these apps., however, is an inferior prominence at the base of each, which is best seen in an oblique view from above (pi. 20: 7, 10). The anal apps. of the female are about as long as the dorsa of 8 and 9, or slightly shorter, and are shaped as in lineata, each with a small terminal spine. The females exhibit the usual range of colour variation as in the other subspecies of intenupta. Measurements. Total length $ 67-68, 9- 61-66, abd. $ 45-47, $ 42-45; h. w. $ 41-43, $ 41.0-42.5; h. f. # $ 8-9; w. hd. 8 9.0-9.3, $ 8.5-9.3; pt. $ 3.0-3.5/3.0-3.6, $ 3.0-3.9/3.0-3.8.

Habitat and range. Nothing distinctive of the habitat appears to have been recorded; it is probably not essentially different in any of the subspecies of interrupta. Southeastern B.C., mainly in the Selkirks, s. through Wash., Ore., Colo, and Utah to N. Mex. Distribution in Canada. B.C.—Field, Kaslo, Nelson, Golden. Its known area of distribution thus includes the Rocky Mountains, Selkirks and the Gold Range. Field notes. Nothing seems to have been recorded about the habits of interna but there is no reason to suppose they differ from those of the other subspecies of interrupta which are probably all essentially alike. There is complete intergradation between interna and lineata northward and eastward and apparently also westward, although in the United States the distributional area of interna appears to be fairly well isolated from that of lineata. Further study is needed, however, to determine this point accurately. Aeshna canadensis Walker. (PL 7: 3, 4; pi. 8: 1, 2; pi. 9: 3; pi. 15: 6; pi. 21: 3, 4; pi. 26: 4) Aeshna canadensis Walker, Can. Ent., 40: 384, 389, 451, 1908; Univ. Toronto Stud., Biol. Ser. no. 11, p. 135,1912. Aeschna clepsydra Selys, Ent. Mag., 2: 242,1875. Aeschna "Y' Williamson, Ohio Nat., 7: 145,1907. This is the commonest Aeshna of still marshy waters in the early summer in southern Ontario and probably throughout the mixed forest region of eastern Canada. It is also common in southwestern British Columbia. Male. Labium dull yellow or drab to dull bluish stained distally with reddish brown, the palpi tinged with greenish blue; face pale bluish or greenish, anteclypeus dark brown,

FAMILY AESHNIDAE

69

fronto-clypeal suture with only a fine brown line, T-spot heavy, rather strongly convex in front; occiput pale yellow, margined laterally with black. Thorax chocolate brown with a gray bloom beneath; dorsal stripes green, sometimes bluish behind, pointed in front, widened at the rear ends, the widened parts often separated as distinct spots; lateral stripes broad but irregular, the first stripe generally blue above, green below, sometimes entirely green or rarely all blue; broadly rounded at the lower end, deeply constricted in front near the middle, widening again above the constriction to about half its width below, and giving off rearward a short narrow spur from its upper end; second thoracic stripe blue, often green below, sometimes wholly green, narrow and pointed below, greatly widened at upper end. Legs dark brown, front femora with a pale streak on proximal half of posterolateral surface. Wings hyaline, costal veins brownish yellow, pt. dark smoky brown above, pale yellowish brown beneath; membranule of hind wings wholly dark smoky brown. Abdominal spots much as in eremita and interrupta but with ML on 5 to 7 larger; most of the spots azure blue, except MD which is yellowish. Sup apps. similar to those of interrupta but slightly longer than segs. 9 + 10 and tapering distally to more acute apices, which are somewhat decurved and terminate in a minute spine; dorsal carina moderately elevated, bearing 5 to 6 minute denticles; inf. app. elongate triangular, about three-fifths as long as sup. apps. Auricles with 3 or 4 teeth, spines of ant. lamina short, not reaching level of hamular processes, directed inferocaudad and not projecting below the tergal margins; hamular processes somewhat elongated, proximally parallel and directed forward, the apices approximated, bluntly pointed; hamular folds continuous with the processes. Female with dorsal thoracic stripes narrower than in male, often obscure in colour, each divided into an anterior more elongate spot and a posterior shorter and wider spot; lateral thoracic stripes similar to those of male. Lateral abdominal spots somewhat larger, PD smaller than in male. In colour there is the usual wide variation from the pure homeochromatic form, which is rare, through various intergrades to completely heterochromatic females. In this type the general coloration is yellowish to grass green with the lateral spots of the abdomen, particularly AL and ML, usually of a more bluish green than PD and PL. Legs somewhat paler than those of male; wings often flavescent, even in old individuals. Genital valves with apices not elevated, lateral carinae percurrent, feeble in basal third or fourth, prominent beyond; ventral surface slightly silicate; styli about .66 mm. long, or half the length of dorsum of 10; basal plate of usual size, the free margin straight; apps. not longer than 8 + 9, generally shorter, widest a little beyond the middle, the width equal to one-sixth or one-fifth of the length, apices rounded or roundangulate, without a terminal spine. Anx $ $ 17-22/12-15, pnx $ $9-13/11-17, usually 2 paranal cells between A2 and A3; 3 or 4 rows of cells between forks of I R3 at level of distal end of pt., and 3-7 cells between the forks at the margin; 3 or 4 (rarely 5) rows between I R3 and Rspl where most widely separated; cells in triangle 4 or 5, usually 5/4; cross-veins under pt. 2—4, usually 3. Measurements. Total length $ 64-72, $ 66-73; abd. $ 46.0-51.5, $ 45-49; h. w. $ 43.0-46.5, $ 42.5-47.3; h. f. $ $ 7.5-8.0; w. hd. $ $ 9.5-10.0; pt. $ 3.0-3.5/3.2-3.5, $ 3.5-4.2/3.5-4.2. Nymph (pi. 30: 4; pi. 33: 2). Head widest a little behind middle of eyes which are moderately prominent; lateral margins of head moderately oblique, nearly straight; posterolateral corners more rounded than in eremita but less so than in interrupta; hind margin approximately straight; antennae 7-segmented; folded labium about five-eighths as broad at base as at distal articulation, the greatest width being equal to about 70 per cent of the length; proximal three-fifths with sides slightly divergent distad and slightly convex; distal two-fifths of sides more decidedly convex; ligula broadly obtusangulate, little produced; palpal lobes rather slender, narrowing somewhat distad; the laterodistal

PLATE 8

Wings of Aeshna canadensis Walk., illustrating the two venational systems: above, the Tillyard-Fraser system, and below, the Comstock-Needham.

FAMILY AESHNIDAE

71

angles well rounded, mesal angles with distinct tooth, the whole distal end of the palpus having the appearance of ^i very abrupt end-hook. Supracoxal processes about equal in length, the posterior slightly stouter. Abdomen broadest at seg. 6 or 7; lat. spines on 6-9, not spreading, those on 6 extending halfway, or less, toward the hind margin, those on 8 to the margin or slightly beyond, on 9 about as far as middle of 10. Cerci slender, about three-fifths as long as paraprocts. Ovipositor nearly reaching posterior margin, genital valves about two-fifths as wide as long. Head behind eyes with a rather narrow pale margin, which is continued over the pronotum and mesothorax, becoming diffuse on latter. Thorax otherwise nearly uniform; legs also concolorous. Abdomen longitudinally striped, a dark median stripe between two pale ones, these becoming less distinct caudad and more or less obsolete on 10. These stripes are for the most part well defined with the margins nearly straight and subparallel; the median stripe solid and dark in front, more or less broken behind into subcontinuous dark blotches on the base of each segment. Sides of abdomen brown, much paler than median stripe. Length 35.0-39.5; prementum 5.5-6.0; abd. 25-29; w. abd. 7.0-7.5; h. w. 8.5-9.5; h. f. 6.0-6.6; w. hd. 7.8-8.0.

Habitat and range. Quiet marshy or bog-margined lakes, ponds or sluggish streams. Nfld. and n. Que. to B.C., s. to Conn., W. Va., Md., 111., Mo., and Wash. Distribution in Canada. Nfld.—Spruce Brook. N.S.—Digby, Annapolis, Cumberland, Colchester, Pictou, Halifax, Victoria (C.B.) counties. N.B.— St. Mary's Bay, St. Andrews, Bocabec Lake, Sackville. P.E.I. (H. C. White, July 8, 1944, 1 $ ). Que.—Magdalen Is.; Seven Isles; Eastman; East Bolton; Montreal; Ste. Therese; Aylmer; Hull, Wakefield and other stations in the Gatineau Valley; Cascapedia, Mont Tremblant Park; La Ferme, Abitibi Co.

Abbreviations 1A—anal T-triangle al— anal loop AJ— first anal A2— second anal an—antenodal cross-veins, 1st series A3—third anal an'—antenodal cross-veins, 2nd series arc— arculus C—costa b—bridge Cu—cubitus bv—brace vein Cu + A— cubitus + anal cs—cubital space Ou* —nrst cubital Cu2—second cubital mb—membranule I R2, 1 R3—Radial intercalary veins ms—median space Mj, M2, etc.—branches of media (a) pn—postnodal cross-veins MA— anterior media (b) (the posterior pst—post-trigonal cells media is absent in all recent Odonata ) pt—pterostigma s— subtriangle Mspl—median supplement N—nodus sn— subnodus R—radius spt— supratriangle TT» T» 1 „_ -1- _ _ f „_ _!• _

72

THE ODONATA OF CANADA AND ALASKA

Onf.—Essex, Kent, Peel, York, Dufferin, Ontario, Northumberland, Bruce, Grey, Simcoe, Lennox-and-Addington, Leeds, Carleton and Renfrew counties; Muskoka, Parry Sound, Algonquin Park, Nipissing, Timiskaming, Manitoulin, Thunder Bay and Kenora districts. Man.—Westbourne, Treesbank, Victoria Beach, Winnipeg, Husavick, Township of Ronge, Lake Atikameg. Sask.—Prince Albert. Alta.—Red Deer. B.C.—Vancouver L: Victoria, Nanaimo dist., Forbes Landing; Vancouver; Chilliwack; Hope; Harrison Bay; Malakwa; Salmon Arm; Prince George. The known northern limit of the range is as follows: La Ferme, Que. (48°35'N), Favourable Lake, Ont. (53°N), L. Atikameg, Man. (54°N), Prince Albert, Sask. (53°3(yN) and Prince George, B.C. (54°N). Field notes. A. canadensis develops among the rushes and sedges along the margins of lakes and sluggish streams and is also not uncommon in sphagnum bog ponds. Robert (1953) makes the following interesting observation of this species in Mont Tremblant Park, Que., "Espece tres repandue dans toute cette region, mais particulierement abondante quand une zone de vegetation inondee entoure le lac. Les barrages construits par les castors creent sans doute le milieu ideal pour le pullulement de Tespece." This is a common dragonfly in the Eastern Provinces, particularly in the zone of mixed conifers and deciduous trees. It is one of the earliest to appear on the wing. In southern Ontario it may sometimes be seen as early as the third week in June, but the usual time for tenerals to appear is the last week of June or the first week of July. Robert (1953) gives July 8 as the first day of its flight period in 1952. By the middle of July in southern Ontario it has usually attained its peak and may sometimes be seen in large numbers about the sunny borders of woods, especially pine woods. Here the young adults may be seen sunning themselves on the trunks of trees or hanging from the twigs. On hot sultry days they fly restlessly to and fro among the trees on the lookout for their prey. By August most of them have returned to the lakes or ponds and may be seen skirting the water's edge over the cat-tails or sedges. Such individuals are males and are patrolling a more or less definite beat. Now and then a male may be seen to drop among the rushes and then emerge with a female in copula. Apparently copulation does not take place far from the water as it often does in other species of Aeshna such as constricta. A. canadensis is still common at Lake Simcoe in mid-September. Robert records it from Mont Tremblant Park until the first of this month, but apparently no collecting was done after that date. The flight period for Ontario is long, June 21 to September 27.* Oviposition is of the usual Aeshna type and the female supports herself on the stems of emergent plants, submerges the end of the abdomen and introduces the eggs into the stems below the surface. Beyond this we have not observed the process. Robert (1944) notes that the females usually oviposit in the open marsh and only rarely along the lake margins. *In British Columbia a month later in beginning, July 25 to September 29.

FAMILY AESHNEDAE

73

In the Prairie Provinces A. canadensis becomes rarer westward and probably fails to reach the Rocky Mountains, although it reappears in British Columbia, particularly on the west coast, which it probably invaded via Washington. According to Whitehouse (1941) it is plentiful enough in this part of the country, even on Vancouver Island, as indicated by the following passages: "Hunting for flies it will follow the contour of the lake shore, entering and searching the low bushes in the most systematic manner. It is consequently very easy to net. At Forbes Landing it was one of the Aeschnas flying on the Lower Campbell Lake Shore at dusk. In point of fact canadensis in that district was a nuisance, for with nine species of the genus on the wing I was searching for two more. This meant that every passing Aeschna must be netted for positive identification." Aeshna verticalis Hagen. (PL 15: 5; pi. 21: 1; pi. 26: 3) Aeschna verticalis Hagen, Syn. Neur. N. Amer., p. 122,1861. Aeshna verticalis Williamson, Ohio Nat., 7: 150,1907. Aeschna juncea L. var verticalis Hagen, Calvert, Trans. Amer. Ent. Soc., 20:284,1893. Aeschna propinqua Scudder, Proc. Boston Soc. Nat. Hist., 10: 214, 1866 [in part], A late summer species of medium size, very like A. canadensis but with the thoracic stripes all or nearly all green. Male. Labium dull grayish, obscured with reddish brown, palpi pale blue or plumbeous; labrum pale green, margined above and below with black; face yellowish green with narrow black eye margins, anteclypeus brown; fronto-clypeal suture with only a fine brown line; T-spot heavy, the stem generally short with divergent sides; yellow area of vertex not quite reaching lateral ocelli; occiput greenish yellow; rear of head black. Thorax dark brown with a slight grayish bloom beneath. Dorsal stripes conspicuous, green or yellowish green, 4 mm. long, pointed in front, widening to 1.5 or more at the ante-alar sinus; lateral stripes yellowish green to pea green, the first stripe widest below, somewhat narrowed above, with a slight backward bend near its middle, then resuming its former course and giving off a broad posterior offshoot from the upper end; second stripe narrower, straight and pointed below, widened by a forward curve from the upper end; interalar tubercles blue-green and green. Abdomen with the usual blue-spotted colour-pattern. Segs. 1 and 2 brown, 1 with dorsal spot blue, lateral spot green; 2 with PD blue, AML bluish geen to blue; remaining segs. with the usual pattern, MD pale green, the other spots blue; PL usually on 3 and 4 only. Wings hyaline, costal veins brownish yellow; pt. dark smoky brown above, pale and more yellowish below; membranule of hind wing smoky brown, uniform or slightly paler at base. Sup. apps. slightly longer than 9 -f- 10, similar to those of canadensis but with the mesal margin appearing less sinuate in dorsal view, the distal part being straight where in canadensis it is concave. Sup. carina moderately elevated distally but without any denticles; inf. app. elongate-triangular, barely more than half as long as the sup. apps. Auricles with 3 (2—4) teeth; spines of ant. lamina longer than in canadensis and other related species, straight and acute, directed inferocaudad; hamular processes directed inferomesad, consisting of a short broad base and a slender distal papilla, which is longer than those of eremita and interrupta; hamular folds continuous with the processes, forming an ear-like clasper, more open than that of canadensis.

PLATE 9

Wings of Aeshnidae: (1) Boyeria grafiana $ ; (2) Basiaeschna Janata $ ; (3) Aeshna canadensis $.

FAMILY AESHNIDAE

75

Female extremely similar to that of canadensis but differing in the form of the lateral stripes of the thorax in the same way that the male does. The first stripe is less constricted near the middle, the front margin being less strongly bent and the posterior offshoot wider; the second stripe has no backward offshoot which is a constant feature of canadensis. The extent of colour variation is still uncertain. We have seen no purely homoeochromatic female. Generally the markings are mostly green, except the lateral spots of the abdomen, which are more or less bluish, but completely heterochromatic females with the light markings all green or yellow-green are not rare. The wings vary from hyaline to a moderate degree of flavescence. The pterostigmata are as usual somewhat paler than in the male. Genital valves as long as dorsum of 9, lateral carinae very prominent, in ventral view nearly straight, bounding a space that is broadest in the proximal two-fifths, thence narrowing to the truncated apices, which bear each a minute pencil of whitish hairs; basal plate of ovipositor with hind edge straight; styli 6-7 mm. long, half as long as dorsum of 10; anal apps. about as long as 8 -f- 9, slender, oblanceolate, widest at about three-fifths of the length, apices rounded. Anx $ 9- 16-20/12-15; pnx 10-15/13-17. Two paranal cells between A2 and A3; 3 rows of cells between the forks of I R3 at the level of distal end of pt, usually 4 rows of cells (rarely 3) between I R3 and Rspl; cells in triangle normally 4 or 5, cells in spt. 4-5/3-4; cross-veins behind pt. #2-3(4), 9 3 ( 2, 4). Measurements. Total length $ 62-72, 9 64-69; abd. $ 42.0-51.5, 9 42.0-50.0; h. w. £ 41-47, 9 42-46; h. f. $ 9.5-8.0, 9 8-9; w. hd. $ 9 9.0-9.7; pt. $ 2.9-3.3/2.7-3.4, $ 3.2-4.3/3.1-4.0. Nymph (pi. 30: 3). Head widest across the vertex, eyes moderately prominent, appearing in dorsal view most convex a little behind the middle; lateral margins barely convex or straight, passing into well-rounded hind corners; hind margin in direct dorsal view barely excavate; antennae 7-segmented, folded labium widest at distal end, the width here being equal to two-thirds of. the length; width at base of prementum slightly more than half its length; sides proximally nearly straight and slightly divergent, in distal three-sevenths moderately convex; ligula broadly obtusangular with a small median notch; palpal lobes scarcely narrowed distally, distal ends truncate, with edges of opposite lobes parallel, the lateral angles somewhat abruptly rounded, the mesal angles somewhat greater than a right angle and terminating in a small tooth or end-hook. Supracoxal processes of nearly equal length, the posterior one a little stouter, their apices somewhat divergently curved. Lateral spines on abd. segs. 6 to 9 not at all flaring, those on 6 reaching one-fourth to one-third of the distance to the base of 7; those on 8 reaching as far as base of 9 or nearly, and those on 9 almost halfway to the hind margin of 10. Anal pyramid as long as 9 + 10; paraprocts only slightly surpassing epiproct; cerci reaching to about three-fifths the length of the pyramid; ovipositor just reaching hind margin of 9. General colour (exuv.) dusky brown; thorax, legs and wing-sheaths uniform brown, abdomen with a broad dark unbroken median stripe extending the entire length from seg. 1 to 10; with a dorsolateral pale stripe on each side usually a little narrower than the dark stripe except in front; bounding the pale bands laterally are wider areas of the ground colour bearing the darker puncta which are usually a little more heavily marked than in canadensis', and laterad of these are somewhat paler marginal zones bounded mesally by the dorsolateral muscle-scars.

76

THE ODONATA OF CANADA AND ALASKA

Length 36.5-40.5; abd. 26.0-27.5; w. abd. 8.0 (dry exuv.); h. w. 8-9; h. f. 6.6-7.0; w. hd. 8.0-8.3.

Habitat and range. Spring ponds, marsh-bordered lakes, N.S. to Minn., s. to Md., N.C., Ohio, Ind., 111., and Iowa. Distribution in Canada. N.S.—Clementsport, Annapolis Co. N.B.—St. Andrews, Charlotte Co. Que.—Aylmer. Ont—Essex, York, Bruce, Simcoe, Leeds and Carleton counties; Muskoka Dist. Field notes. In Canada this species is local and variable in numbers. The habits of the adult appear to resemble those of A. canadensis. Like this species it flies about the borders of woods or in sunny glades in their midst. In its flight and its habit of basking in the sun on the trunks of trees and of coming to rest under their branches, it is also like canadensis, but it is not often associated with this species, since it normally appears nearly a month later. Most of our records, both from the United States and Canada, are dated August and September. The entire flight period in Ontario omitting occasional very early records, is from July 14 to October 11. Our earliest Ontario record is June 21, at Gananoque, and there are at least two earlier records from the United States, one from Chicago of June 13 and another from Milwaukee Co., Wis., of June 14. In regard to breeding places A. verticalis has been an elusive insect. On September 22, 1940, we observed a few males patrolling a small oxbow pond with a stand of Typha, at Highland Creek, east of Toronto, but never at DeGrassi Point, Lake Simcoe, where most of our specimens were taken. Their sudden appearance in numbers in this district suggests immigration from some other locality. After many years we finally found A. verticalis in transformation, at Clementsport, N.S. On July 5, 1940, while collecting in this vicinity, we were guided to a pond in a boggy pasture by the resonant croaking of Green Frogs (Rana clamitans Latr.). This pond had been formed by the damming of the outlet of a springy bog on a partly wooded slope. The pond covered about an acre and most of this area supported a dense stand of a coarse sedge (Carex sp.). Our first visit to the pond, made in the forenoon, yielded nothing of interest, but we returned there about 5.30 P.M. on the same day and found two newly emerged aeshnas, a male and a female with their exuviae. "They were white and opaque with folded wings but, when their colours had developed they proved to be verticalis" (Walker, 1941c). The pond was visited again on July 6 and 8 and newly emerged aeshnas were found on both days, together with their exuviae. These had probably emerged early in the morning. Nearly forty exuviae were found altogether on the three days and the time of emergence may thus be quite variable. "No further visits to the pond were made until July 20, when a few exuviae were found but no adults. The period of emergence was apparently over. All of these exuviae

FAMILY AESHNIDAE

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were clinging to the stems or leaves of the sedges, usually eight to twelve inches above the water" (Walker, 1941c). We have only two pairing records of A. verticalis, both in September. One of these is from Toronto, September 12, 1907, the pair having been observed at a small forest pond near the Humber River, the other at an oxbow pond in the valley of Highland Creek (east of Toronto) on September 22, 1940. Aeshna clepsydra Say. (PL 15: 7; pi. 21: 5, 6; pi. 23: 3; pi. 26:5) Aeshna clepsydra Say, J. Acad. Phila., 8: 12,1839. A medium-sized eastern species of slender form, remarkable for the variegated colour-pattern of the thorax. Male. Labium pale yellowish or greenish, middle lobe stained with brown; labial palpi blue or green; labrum pale green, anteclypeus reddish brown, face bluish green to olivaceous, with a heavy dark line on the middle part of the fronto-clypeal suture; T-spot very heavy, stem with sides straight and parallel or nearly so; yellow area of vertex nearly reaching lateral ocelli; occiput lemon yellow; rear of head black. Thorax very dark brown in humeral region and upper part of sides, paler on dorsum and covered ventrolaterally with a grayish bloom. Dorsal stripes light green, somewhat crescentic with anterior ends pointed and turned laterad, posterior ends widened and separated only by the dorsal carina; lateral markings broad and irregular, green and bluish; first stripe widest below, where it is separated by the mesopleural suture from a triangular antehumeral spot; upper part crescentic, terminating above in a forwardly curved spur; second stripe triangular, very broad above; between the two main stripes are two smaller spots, a larger rhomooid spot, enclosing the metaspiracle and a smaller one obove it. Legs reddish brown; femora somewhat darker, no pale streak on fore femora. Wings hyaline, costal veins tawny; pt. smoky brown, pale yellowish brown beneath; membranule of hind wings wholly dark smoky brown. Abdominal spots of the usual pattern with slight variations; ground colour dark brown, paler in front of the transverse carina, darkening on the more posterior segments, blue spots pale, MD yellowish; PD spots increasing in size caudad, triangular on 8 and 9, connate behind on 10. In addition to the usual dorsal and lateral spots there is a pair of pale ventral spots on 4-7. Abdomen slender, spines of anterior lamina short and blunt, directed inferocaudad, not projecting below tergal margins; hamular processes directed anteromesad, without a distinct apical tubercle but surface divided by an oblique ridge; hamular folds like those of eremita, verticalis, etc. Sup. apps. barely longer than 9 + 10, the narrower basal part shorter than usual, the wider distal part relatively narrower with edges subparallel in the middle region, apices moderately acute but not decurved, with a slender terminal spine; sup. carina scarcely visible in lateral view, but with 3-5 denticles on the apical third. Inf. app. elongate triangular, three-fifths as long as sup. apps., tapering to apex, which is surmounted by a pair of minute spines. Female. Colour-pattern of thorax similar to that of male, abdominal pattern with the usual differences. Coloration of the few specimens seen in life duller than in male, PD spots green. Dorsum of 9 about five-sevenths of length of 8; ovipositor similar in length and form to that of canadensis, styli scarcely more than .5 mm. long. Anal apps. shorter than 8 -f- 9, oblanceolate, greatest width about one-fifth of length, apices rounded. Anx $ 15-20/11-13, 9 16-19/11-13; pnx $ 9-13/10-17, $ 9-12/11-15; h. w. with 6-7 paranal cells, anal triangle 2-celled; I R3 forking at level of 1 to 3 (f. w.) 3-4 (h. w.) cells before pt.; with 3 rows of cells between the forks opposite distal end of pt., and

78

THE ODONATA OF CANADA AND ALASKA

4 rows across widest part of Rspl loop; cells in triangle typically 4-5/4; cells in spt. typically 4/3. Measurements. Total length £ 67-70, $ 67-68; abd. $ 45.5-49.0, $ 46-48; h. w. 3 40-47, $ 43-44; h. f. 3 $7-8; w. hd. $$ 9.0-9.5; pt. S 3.4-3.6/3.2-3.5, $ 4.4-4.5/4.2-4.4. Nymph (pi. 30: 5). Very similar to canadensis from which it differs chiefly in the form of the palpal lobes of the labium. Eyes and posterolateral angles of head very slightly more prominent; antennae 7-segmented; folded labium widest at distal end, width here 65 per cent of the length, width at base of prementum seven-elevenths of its length; distal two-fifths of lateral margins about as convex as in canadensis', ligula moderately produced, subarcuate; palpal lobes (pi. 30: 5) a little more slender and tapering to a curved end-hook that is much less abrupt than in canadensis. Supracoxal processes somewhat shorter than in the latter species, bluntly conical, about equal in length, or the posterior one a little shorter. Lateral spines of abdomen somewhat longer than in canadensis, those on 6 extending half way to the hind margin of its segment, increasing in length caudad, those on 9 extending as far back as the proximal two-thirds of 10. Colour-pattern much as in canadensis but pale marginal stripes of head and thorax wider; longitudinal stripes of abdomen extending to end of 10, their edges almost straight throughout their length. The dark median stripe is more even in depth of shade, the puncta not being marked with darker brown; dorsolateral and lateral puncta also inconspicuously marked. Length 36.5-40.0; abd. 23-28; w. abd. 7.0-7.5; h. w. 8.2-9.0; h. f. 6.0-6.2; w. hd. 7.5-8.0

Habitat and range. Shallow bays with emergent vegetation and marshbordered lakes. N.S. to Wis., s. to N.J., Ohio, Ind., and Iowa. Distribution in Canada. N.S.—Lake Kedgemagooge, Annapolis and Queen's counties; Lily Lake, Antigonish Co.; Moser River, Halifax Co. Ont.— Essex, Northumberland and Simcoe counties; Muskoka Dist. Field notes. This is an eastern species, apparently most common on the Atlantic seaboard, particularly in the New England states. In 1915 (Walker, 1915) we reported it from Go Home Bay, Georgian Bay, Ont., where it was stated to have been more frequently found than any other species of Aeshna except A. canadensis. Ordinarily, however, it appears to be very rare in Ontario and has never been reported from Quebec. Several have been received from Nova Scotia and judging from its comparatively common occurrence in Maine and Massachusetts, we would predict that Nova Scotia and Prince Edward Island will prove to be the provinces where it is most plentiful. At Go Home Bay nymphs were occasionally dredged from beds of rushes and other emergent plants along the borders of shallow ponds or bays. Two males taken from such habitats emerged on July 25 and 28, 1910, and two other males taken in July were nearly ready to emerge. The adults were in flight during the latter part of July and in August. Like A. canadensis they new over the rushes and sedges of their breeding haunts or in the open woods farther away from the water. They were also seen to patrol the shore line more or less closely, as other aeshnas do. A. clepsydra is a late species, New England records range from August 6 to

FAMILY AESHNIDAE

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October 1; those from Nova Scotia August 2 to September 11; Ontario July 19 to September 12; and Indiana August 24 to September 1. Aeshna tuberculifera Walker. (PL 15: 8; pi. 21: 7, 8; pi. 24: 4; pi. 26: 6) Aeshna tuberculifera Walker, Can. Ent, 40: 385, 387, 451, 1908; Univ. Toronto Stud., Biol. Ser., no. 11, p. 152,1912. Aeshna juncea verticalis Calvert, Occas. Papers Boston Soc. Nat. Hist., no. 6, p. 23,1905 [in part]. A slender species of rather large size and broad straight lateral thoracic stripes; seg. 10 wholly black. Male. Labrum obscure yellowish or olivaceous, stained with reddish brown toward the free edges; labium light green with very narrow dark margins; face olivaceous except the anteclypeus, which is reddish brown; frons paler along the sides and above, frontoclypeal suture with only a fine brown line; T-spot with sides of stem straight and somewhat divergent; occiput pale bluish green, the anterolateral margins blackish; rear of head black. Thorax dark brown, deepening to black around the lateral stripes with the grayish bloom beneath; dorsal stripes pea green, nearly straight, lower ends pointed, upper ends reaching the ante-alar sinus, widened and separated mesally by 1.0-1.5 mm.; lateral stripes blue above, pale green below, straight, the first stripe rounded below, narrowing somewhat in the upper half but widening again at the upper end; second stripe with edges for the most part straight and subparallel. No spots between the stripes or at most a minute dot; spots between and at bases of wings blue. Legs dark brown, nearly black on the tibiae, tarsi and underside of femora; fore femora without a pale streak. Sees. 1 and 2 dusky brown, the others blackish, the blue spots somewhat reduced; lateral spot of 1 wanting; most of the lateral spots small or aosent and PD spots also somewhat smaller than usual; 10 entirely without pale spots. Wings hyaline or slightly flavescent in tenerals; costal veins reddish brown, pt. dark brown, membranule of hind wing dark smoky brown, fading into pale grayish at base. Sup. apps. as long as 9 -f- 10 or slightly shorter, similar to those of canadensis or verticalis, but the stem-like basal part wider as viewed from above and showing a prominent inferior tubercle at about the proximal fifth of the appendages' length when viewed from the side; lateral margin subparallel in the distal half, apices somewhat abruptly and obtusely pointed, not decurved but with a small deflexed terminal spine; dorsal carina proximally indistinct, distally raised a little above the level of the lateral margins; without denticles. Inf. app. triangular with nearly straight sides one-half to three-fifths as long as sup. apps.; in profile very gently upcurved. Auricles with 4 or 5 teeth. Spines of ant. lamina short and blunt; hamular processes short and very broad, the blunt apices with no indication of a tubercle; hamular folds continuous with the hamular processes, with thickened margins. Female very similar to male, usually homoeochromatic, although we have seen one female from Hampden, Mass. (Walker, 1912a) in which the PD spots on the posterior segments are yellow and were probably so in life. We can therefore only say that the blue-spotted females are the usual form, the green- or yellow-spotted ones exceptional. The dorsal thoracic stripes are, as usual, somewhat narrower than those of the male, the lateral abdominal spots larger and the PD spots slightly smaller. The wings are sometimes slightly flavescent. Abdomen slightly widened at junction of 9 and 10; genital valves as long as dorsum of 9, in profile arcuate toward the base, apices slightly elevated; lateral carinae prominent, in profile sinuate, in* ventral view straight; basal plate of ovipositor with hind edge straight; spines on ventral surface of 10 few and scattered,

PLATE 10

Wings of Aeshnidae (1, 2) and Gomphidae (3); (1) Gomphaeschna furcillata $ after Needham and Westfall; ( 2 ) Anax junius $; ( 3 ) Ophiogomphus severus $.

FAMILY AESHNIDAE

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rather coarse; styli 1.5 mm. long or about as long as dorsum of 10; anal apps. about as long as 8 + 9, the greatest width before the middle slightly more than one-fifth of the length, apices acute or roundly angulate, sometimes with a minute terminal spine. Anx 18-22/11-16; pnx 11-18/13-18; usually 2 cells at tip of 2nd anal interspace; anal loop with 9-11 cells. I Ro forking usually 3-4 costal cells before proximal end of pt.; 3 rows of cells between forks of I R3 opposite distal end of pt., and 3 or 4 cell rows between I R3 and Rspl. Measurements. Total length $ 72-74, 9- 71-78; abd. $ 47.5-52.5, 9- 45.0-54.5; h. w. 4 45.5-49.0; $ 44.0-50.5; h. f. $ $ 8.5-9.0; w. hd. $ 10.0, $ 9.0-10.5; pt. $ 3.4-3.8/3.3-3.5, $ 3.7-4.2/3.5-4.0. Nymph (pi. 31: 1; pi. 34: 4). Longer and relatively more slender than other species of Aeshna in our fauna with a pattern like that of interrupta and eremita, though less distinct. Eyes slightly less prominent than in the species hitherto treated, with a somewhat longer anteroposterior diameter; lateral margins of head passing by well-rounded corners into the nearly straight or slightly concave hind margin; antennae 7-segmented; folded labium attaining the level of the hind coxae, slightly longer than hind femora, its distal width about 55 per cent of the length, basal width of prementum slightly less than half the distal width. Ligula very broadly obtusangulate, palpal lobes with margins parallel, apices squarely truncate, the distolateral angles scarcely rounded, end-hook represented by a small dark tooth. Supracoxal processes acute, the hind process slightly broader than the front one, apices scarcely divergent. Abdomen long and slender, widest at 6 or 7, lat. spines on 6 to 9, not divergent, those on 6 reaching one-third to one-half the distance to hind margin of segment; increasing in length caudad to 8, which reaches margin of segment, on 9 reaching middle or posterior fourth of 10. Cerci three-fifths ( $ ) - o r three-fifths to four-sevenths ( $ ) as long as paraprocts, which are about onefourth longer than epiproct. Ovipositor reaching slightly beyond the hind margin of 10; styli reaching end of ovipositor. Colour in life rather pale olivaceous; pattern similar in the main to that of A. interrupta; head and thorax nearly uniform; femora in proximal half uniform brownish, distal half with a dark annulus between two light ones; tibiae and tarsi concolorous. Abdomen with a median series of pale spindle-shaped spots on segs. 1-7, each partly enclosed by darkened puncta; also laterobasal pale spots on most of the segments; indications of pale blotches about the lateral scars and elsewhere. Length 41-45; abd. 30-32; w. abd. 7.5-8.8; h. w. 9.5-9.9; h. f. 7.7-8.3; w. hd. 8.1-9.0.

Habitat and range. Ponds, especially bog ponds. N.S. to Wis., s. to R.I., Conn., Pa. and Ind.; also in w. B.C. Distribution in Canada. N.S.—Annapolis, Hants, Colchester and Lunenburg counties. Que.—Covey Hill, Masham Mills, Bristol, Mt. Tremblant Park. Ont.—Peel, York, Ontario, Simcoe and Lennox-and-Addington counties; Muskoka Dist. B.C.—Vancouver I. (near Wellington; Forbes Landing). Since this species has not been found between Wisconsin and Vancouver I., B.C., in more than forty years, it appears probable that the eastern and western populations are distinct, although the individuals from the two regions appear to be identical.

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THE ODONATA OF CANADA AND ALASKA

Field notes. This is one of the rarer aeshnas, although occasionally found locally in some numbers. In Canada it is relatively southern, its northern limit being, in the east, Lac de la Grosse (46°17/N) in Mont Tremblant Park, Que., and in the west Forbes Landing, Vancouver Island, B.C. (50°N). It is called a "northeastern species/' however, by Needham and Westfall (1955) since it is not known in the United States south of Pennsylvania and Indiana. It appears to prefer bog-margined ponds or lakes. We first found both nymphs and adults at a small forest lake or pond on Vancouver Island, near Wellington. It was not a sphagnum pond but had a narrow boggy margin and was entirely surrounded by forest. Many years later we found a female ovipositing at the edge of a pond near the Lake of Bays, Muskoka, Ontario. This pond was also slightly boggy and at the edge of a tract of woodland but was not at all of the nature of a sphagnum pond. On July 5, 1945, however, we found two exuviae at the typical sphagnum pond near Buckshot Lake, Lennox-and-Addington Co., Ont. This is a pond with a floating margin, pitcher plants (Sarracenia purpurea) and all the associated flora. Lac de la Grosse, already mentioned, is also described by Robert (1953) as a bog lake with neither inlet nor outlet, situated in a large valley amidst a stand of conifers, and at an altitude between 1,100 and 1,200 feet. Among the associated Odonata were the typical bog forms Nannothemis bella, Nehalennia gracilis, Leucorrhinia glacialis, and six other species of Aeshna. We first found A. tuberculifera at the stage of emergence at the small lake near Wellington, B.C., on July 31, 1913. We visited the lake several times between this date and August 13 and took 5 males, 7 females, 3 nymphs, and many exuviae. A male and a female emerged from two of the nymphs on August 2 and 3. The third nymph was of the penultimate stage and was kept alive until the following spring, moulting in March and thus reaching the last larval stage. It was about to emerge in July but was accidentally killed. (The exact dates have been lost.) Calvert (1938) succeeded in rearing four individuals of tuberculifera from the egg stage to the time of transformation. A female, which had been taken in copula on September 16, 1935, was brought home alive, and on the following day oviposited in a cat-tail leaf (Typha). Pieces of the leaf containing egg-punctures were kept in a jar containing water in a moderately heated room. Hatching of these eggs began on March 13, 1936, and continued until April 5, 85 larvae having been secured. Of these 33 were placed in separate containers for rearing, and from these 2 "transformed to imagos on July 27 and August 3, 1937, respectively, both males, the former as its thirteenth larval moult, the latter as its fifteenth larval moult. Two female larvae died, without transforming, on June 7 and July 17, 1937, respectively, both of them having completed fourteen larval moults; had they lived to adulthood each would, of course, have made at least one more moult" (Calvert, 1938). On the single occasion when we observed this species ovipositing, the

FAMILY AESHNIDAE

83

female supported herself on an emergent plant (not recorded) close to the water and punctured the plant beneath the surface after the manner of most species of Aeshna. Whitehouse (1941), however, who observed oviposition on several occasions, writes as follows: 'The insects—sometimes side by side—would alight on the slim stemmed sedges rising from shallow water. With a hold, possibly four inches from the surface, they would curve their abdomens and punch eggs into the sheathed stem. This was mid-August." This seems to indicate that the insects were wholly above water. We had thought this might be the case, owing to the similarity of the large ovipositor to that of A. constricta, which practises this method, although perhaps not always. The flight period is somewhat late. Ontario dates range from July 5 to September 30. Quebec dates July 27 to September 22; Nova Scotia August 7 to September 12; British Columbia July 26 to August 19. Although our records are not very numerous, it appears that emergence takes place chiefly in July and that the flight period reaches its peak in August, that it lasts well into September in most localities, and in some years until at least the beginning of October. Aeshna juncea Linn widest at about three-fifths the length from base, the width about one-fifth of the length, tapering rather abruptly to rounded or subangulate apices which usually terminate in a minute tooth. Anx $ $ 16-20/11-14; pnx $ $ 9-14/11-15; paranals h. w. $ 5, $ 5-7; anal triangle 2-celled; I R3 forking opposite proximal end of pt. or 1-2 costal cells before pt.; 3 rows of cells between forks of I R3, opposite distal end of pt. and 4(3) rows across widest part of Rspl loop; cells in triangle typically 4-5/4; cells in spt. $ 4/3, $ 3-4/3. Measurements. Total length $ 63-69, $ 61-66; abd. $ 45.5-49.7, $ 42.5-48.0; h. w. 3 42-46, $ 39.5-46.5; h. f. $ 8.0-8.5, $ 7.5-8.0; w. hd. $ $ 9-10; pt. $ 3.5-4.3/3.5-4.0, $ 3.7-4.9/3.5-4.3. 'Nymph (pi. 31: 2; pi. 33: 3). Very similar to canadensis and verticalis, but less conspicuously striped. Head widest a little behind middle of eyes, which are moderately prominent, lateral margins slightly more oblique than those of the above species, posterolateral angles broadly rounded, back of head barely emarginate; antennae 7-segmented; folded labium widest a little before the distal articulation, the width here being nearly two-thirds of the length, lateral margins slightly divergent in the proximal three-fifths, strongly convex distally, ligula broadly obtusangulate, not rounded; palpal lobes squarely truncate, their sides subparallel, distolateral angles scarcely rounded, distal margins closely parallel, mesal angles with or without a small tooth-like end-hook. Supracoxal processes prominent, about equal in length, the posterior process slightly stouter at base. Abdomen widest at 6; lateral spines on 6 to 9, those on 6 minute, those on 8 reaching about three-fourths of the distance toward base of 9; those on 9 as far back as middle of 10, or a little shorter. Paraprocts a little shorter than 9 -f- 10, cerci straight and substyliform, tapering to small slightly incurved apices, half to four-sevenths as long as the paraprocts. Apices of female genitalia just reaching hind margin of sternum of 9. Head and thorax almost uniform brownish (exuv.), postocular margins sometimes paler; legs concolorous. Dorsum of abdomen with two longitudinal pale stripes, fairly well defined on the first four or five segments, but fading caudad, disappearing or nearly

FAMILY AESHNIDAE

85

so at 9; median dark area little or no darker than the general ground colour, but divided on the more anterior segments by a more or less distinct pale line; sides of abdomen broken by lateral muscle-scars, forming a pale interrupted wavy line; puncta dark. Length 37-41; abd. 26-29; w. abd. 6.8-7.0; h. w. 6.8-7.8; h. f. 6.2-6.9; w. hd. 7.7-8.0.

Habitat and range. Ponds and ditches, especially in peaty soil, also shallow bays or sluggish streams with emergent vegetation. Nfld. and Labr. to Hudson's Bay, Great Slave and Great Bear Lake to the Mackenzie Delta, Yukon and Alaska, s. to N.H., Que., n. shore of Lake Superior, Ont, n. Man., the Alberta Rockies and B.C., and farther s. along the mountains to Wyo. and Colo.; also in northern and alpine Europe and Asia. Distribution in Canada and Alaska. Nfld.—St. John's. Labr.—Hopedale; Goose Bay; Nain. Que.—Magdalen Is., Great Mecatina L, Mt. Lyall, 1,500 ft.; Natashquan; Thunder River; Moisie Bay; Seven Isles and other stations on the north shore of the Gulf of St. Lawrence; La Ferme, Abitibi Co.; Point Comfort; Rupert House and Ft. George, James Bay; Great Whale River, Hudson's Bay; Knob Lake; Fort Chimo, Ungava. Ont.—Cochrane: Lake Abitibi and Moosonee, James Bay; Kenora: Ft. Albany, Ft. Severn. Man.— The Pas; Lake Atikameg, Pikwitonei; Gillam; Churchill, Hudson's Bay. Alta.—Banff. B.C.—Field, Kamloops, Leanchoil, Lumbey, Penticton, Quesnel, Sinclair; Cultus Lake; Vancouver I.: "Forbidden Plateau" (3,20(X), northern V.I.; Queen Charlotte Is.; Prince Rupert and Atlin dist. N.WT.-Keewatin Dist.: Eskimo Pt; Mackenzie Dist.: Ft. Smith; Ft Simpson; Ft. Resolution. Ft. Rae and other stations in the Great Slave Lake region; Ft. Wrigley, Mackenzie River; Cameron Bay, Great Bear Lake; Aklavik and Reindeer Depot, Mackenzie Delta; new record: Hay River, July 8, 1951, 1 $ (P. R. Ehrlich). Yukon T.-Whitehorse; Dawson (1,5000; Dry Creek. AlaskaKenai I.; Norton Sound; Kodiak; Unga L; Shumagen Is.; Nushagak River; Bethel; Kuskokwim River; Admiralty L; Anchorage; Gulkana; Juneau; Ketchekan; Palmer; Seward; Valdez. New records—King Salmon, Naknek, August 3, 1952, 13 4 $ s, W. R. Mason; July 20, 1952, 1 $ teneral, J. B. Hartle. This species is the most abundant Aeshna in Alaska and in the Mackenzie Delta beyond the Arctic Circle. Field notes. This boreo-alpine species inhabits a wide variety of stillwater habitats, showing a preference for peaty waters. We found it first on the Nipigon River, Ont., north of Lake Superior, where it was flying over a shallow reedy section of the stream in company with A. eremita, interruptay canadensis and subarctica. On subsequent occasions, however, we have met with juncea chiefly about smaller bodies of water, such as boggy sloughs or other types of ponds. For instance, we found this species in abundance in the Bow Valley near Banff, Alta., on August 8, 1921, flying over small ponds along the railway. Numerous exuviae were also found on the emergent vegetation surrounding the ponds. Again, at Lowbush, Lake Abitibi, Ont., July 14-20, 1925, we found it along the railway, hawking over the many puddles and ditches formed by the drainage from the peaty soil of a black

PLATE 11

Wings of Gomphidae: (1) Octogomphus specularis; (2) Gomphus (Hylogomphus) brevis; (3) Gomphus (Stylurus) plagiatus after Needham and Westfall.

FAMILY AESHNIDAE

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spruce swamp, through which the railway passes in this district. Another locality where we found juncea in numbers about bog ponds was Prince Rupert, B.C. Here in a boggy clearing were several ponds where nymphs of juncea were common. Many exuviae and occasional emerging individuals were found here during the second half of June. Adults were also found emerging on June 16 from a shallow, spring-fed puddle in a rock-cutting. They were associated with Libellula quadrimaculata and Somatochlora semicircularis, which were also emerging at the same time. The time of emergence at Prince Rupert appears to be earlier than usual. Whitehouse (1941) states that at Atlin, in northern British Columbia, "young males just come to adult coloration, were first taken July 15th, and the flight continued until the end of August when I left for the south." We have no notes on oviposition, but Whitehouse (1941) adds to the above the following: "Females, of both colour forms, were observed ovipositing around the edge of muskeg pools on many occasions; reed stems being grasped and the abdomen lowered some two inches below the surface to the muskeg slime." Robert (1944), who found this species locally in the vicinity of La Ferme, Abitibi Co., Que., also observed females ovipositing among the sedges (Carex) and horse-tails (Equisetum) of the marshes, evidently bordering one or both of the two lakes where this species was taken. A. juncea is well known in Europe, where its life history and habits have been carefully observed by Miinchberg (1930) and otters. The female oviposits in June and August unattended by the male, and usually in the evening. The eggs are inserted into the matted roots of aquatic plants such as Carex, Equisetum, Sparganium, Phragmites (reed-grass), and into sphagnum moss (Schiemenz, 1953). They hatch the following spring and the duration of development is usually four years, rarely only three. Thus the first winter is spent in the egg stage, the second and third and generally a fourth are spent in the larval stage. The observed number of stages is thirteen (Miinchberg). The North American form of A. juncea is known as A. juncea amencana Bart. Aeshna subarctica Walker. (PL 16: 2; pi. 21: 11, 12; pi. 23: 6; pi. 26: 8) Aeshna subarctica Walker, Can. Ent, 11: 385, 390, 451, 1908. Univ. Toronto Stud., Biol. Ser., no. 11, p. 93,1912. Very closely related to A. juncea but easily distinguished by the form of the lateral stripes of the thorax and the longer anal appendages of the female.

88

THE ODONATA OF CANADA AND ALASKA

Male. Head like that of juncea. Thorax dark brown with an olivaceous tinge deepening to nearly black around the lower parts of the lateral stripes. Dorsal stripes yellowish green, complete, strongly divergent below, 4 mm. long, tapering towards each end, but upper ends suddenly widened and separated by about 1.5 mm.; an ill-defined greenish streak immediately in front of mesopleural suture; lateral stripes much narrower than in juncea, light blue above, greenish yellow below, the first stripe widest below, narrowed towards middle, where it is bent obtusely forward, upper end giving oif a slender posterior offshoot Second stripe wider, straight behind, broadly excavated in front; between the two stripes are two narrow yellow spots, the larger and lower one partly enclosing the metaspiracle. Interalar tubercles pale blue, spots at bases of costal veins of wings yellow. Legs dark brown, femora below, tibiae and tarsi blackish; fore trochanters and bases of fore tibiae with a pale streak. Wings hyaline, costal veins, pt. and membranule as in juncea. Colour-pattern of abdomen similar to that of juncea; but some of the spots smaller; lateral spots greenish blue to pale blue; AL rather small and decreasing in size caudad to a pair of dots on 9, when present there; ML larger, increasing in size to 6 or 7; PD somewhat smaller than in juncea, pale green to pale blue, underside of abdomen without pale markings. Sup. apps. slightly longer than 9 -j- 10, similar to those of juncea, the sup. carina raised as in that species, without denticles, apex decurrent and terminating in a minute spine. Spines of anterior lamina, long, straight, tapering to acute apices, directed downward, hamular processes long, fiat, overlapping one another mesally, apices rounded; hamular folds separate from hamular processes, sunk deep in genital tossa, broad, fiat and closely united with each other. Female. Easily recognized by the similarity of the thoracic pattern to that of the male; similar to the female of juncea, differing chiefly in the longer anal apps. and the shorter genital valves. The variation of colour-pattern is similar to that of juncea. "In several specimens seen in hie the coloration was almost like that of the male, the lateral abdominal spots being pale blue or bluish white and PD varying from very pale blue to greenish. In others a2 the pale markings are yellow or greenish yellow" (Walker, 1912). The wings vary from hyaline to deeply fiavescent, the two extremes being usually found in the blue and the yellow-green spotted types respectively. Genital valves not longer than dorsum of 9, strongly compressed distally; lateral carinae distinct only in the distal three-fifths; apices strongly compressed and blade-like, in profile broad and rounded, with a very minute tuft ot hair; styli .5 to .6 mm. long; anal apps. about as long as 8 + 9, oblanceolate, slender at base, apices rounded, with or without a small terminal spine. Anx # 16-20/11-15, $ 16-20/10-14; pnx $ 9-14/10-16, $ 10-14/11-15; h. w. with 4-6 paranal cells, usually 5; anal triangle 2-celled; I R3 forking at level of 1(2) cells (f.w.) or 2 (1-3) cells before pt.; 3(2) rows of cells between the forks at level of distal end of pt.; 3 or 4 rows of cells across the Rspl loop at its greatest width; cross-veins under P t.2-4U),3-£($). Measurements. Total length $ 65-71, 9 63.0-68.5; abd. $ 47.0-51.5, $ 43.5-49.0; h. w. $ 42-46, $ 39.5-44.5; h. f. £ $ 8.0-8.5; w. hd. £ $ 9.5-10.0; pt. 3 3.5-4.0/3.5-3.7, $ 4.1-5.0/3.8-4.8. Nymph (pL 31: 3). Yellowish brown to dark brown, the abdomen more conspicuously marked and more polished than in juncea. Head and thorax, including legs, concolorous, except for traces, sometimes obscure, of a pale postocular stripe, bordering sides of head and pronotum. Pale longitudinal abdominal stripes conspicuous on the first 5 or 6 segments, becoming ill-defined caudad, where they are broken into pairs of anteriorly placed spots, the last and smallest pair on 9; median dark area more distinct than in juncea, but fainter on 2, narrowed at the extreme base of most of the segs. and darkened somewhat anterior to die dorsal puncta; sides of abdomen similar in colour to median area, varied only by the dark puncta, the paler lateral muscle-scars and an ill-defined pale streak just mesad of these scars.

FAMILY AESHNIDAE

89

Head and eyes as in juncea; labium with prementum somewhat less widened distally, the lateral margins less strongly sinuate and not converging to the bases of the palpi; proximal width a little more than three-fifths of distal width; palpal lobes more slender than in juncea, being less than one-half wider than the base or the movable hook at the same level, slightly narrowed toward their apices, which are subtruncate, their distolateral angles well rounded, the mesal angles barely toothed. Supracoxal processes as in juncea or a little more prominent, with coarser scales; abdomen slender, widest at 5 or 6, lat. spines on 7-9, with a vestige on 6; spines on 8 reaching two-thirds or threefourths of the distance to the base of 9; those of 9 to basal third or middle of 10. Paraprocts about as long as 9 -f 10, their apices bent inwards; cerci about two-thirds as long as paraprocts, their inner margins sinuate, apices tapering more abruptly than in juncea and decidedly incurved in the male. Apices of female genitalia barely or not quite reaching hind margin of 9. Len#h 40-42; abd. 27-30; w. abd. 6.7-7.5; h. w. 7.3-7.8; h. f. 6-7; w. hd. 8.3-8.5.

Habitat and range. Sphagnum bog ponds and cold northern swamps. Nfld. to James Bay and the Mackenzie Delta, s.w. to Vancouver L, B.C.; s. to N.S., Mt Tremblant, Que., central Ont, n. Mich, and Man. Also in n. and middle Europe. Distribution in Canada. Nfd.—Humber dist (Cowley); N.S.—Pictou. Que.—Magdalen Is., Anticosti; Thunder River; La Ferme, Abitibi Co.; Mt Tremblant Park; Ft. George, James Bay. Ont—Simcoe Co., a single stray; Nipissing, Cochrane and Thunder Bay districts (new record—Ogoki, July 27-Sept. 8,1952, J. B. Wallis). Man.-Winnipeg; The Pas. B.C.-Field; Tete Jaune; Vancouver I., Courtenay. N.W.T.—Mackenzie: Gros Cap, Christie Bay, and other stations on Great Slave Lake; Cameron Bay, Great Bear Lake; Reindeer Depot. Field notes. This is another holarctic Aeshna, which is now well known in middle and northern Europe, where it is a characteristic species of sphagnum bog ponds as it is with us. Apart from our first capture of this species, a stray female taken at DeGrassi Point, the records of it are chiefly from widely scattered stations in the boreal regions of Canada, the entire range being similar to that of juncea, except for the southward extensions of the latter along the mountain ranges of the west. We first found A. subarctica in some numbers, flying with juncea and other aeshnas on the Nipigon River, but nothing distinctive of its habits was learned. The first station where we found the nymph or rather the exuvia of subarctica was at The Pas, Man. This station was a drainage ditch in a swamp of black spruce and tamarack, which had been dug some years before, alongside an abandoned railway siding at right angles to the main railway cutting. It had no perceptible current except at the outlet in the cutting, but was close to a small, shallow stream flowing quietly through the bog vegetation and expanding here and there into small ponds. Along the stream flew Somatochlora minor Calvert and about the ponds Leucorrhinia hudsonica (Selys) and Coenagrion resolutum (Hagen). At the siding, where the water was still, there were Coenagrion interrogatum (Hagen) as well as C. resolutum, Nehalennia irene Hagen, Aeshna juncea (L.), A. sub-

90

THE ODONATA OF CANADA AND ALASKA

arctica Wlk., Somatochlora franklini Selys, L. hudsonica and Sympetrum danae Sulz., with occasional visits of other species from outside; in general a typical assemblage of boreal dragonflies. It was among the sedges growing in the ditch along the railway siding that we found a male of subarctica with its exuvia together with two other exuviae on nearly the same spot A. juncea was also taken here and several exuviae found. It appeared that juncea had emerged somewhat earlier than subarctica, which had probably only recently begun to transform. Whitehouse, who located subarctica at T£te Jaune, B.C., determined its habitat as "the muskeg pools bordering a large reedy slough. . . . Probably to avoid the wind, the insects were flying low, just over the tips of the moss rising to the surface of the water/' Three other species of Aeshnay palmata, eremita and umbrosa, flew over the slough itself, but A. subarctica confined its movements to the muskeg pools. This conforms to the habits of this species as described by European workers. A third Canadian odonatist, Robert, has reported subarctica from two localities in Quebec, the vicinity of La Ferme, Abitibi Co., and Mont Tremblant Park. He describes the habitat as cold marshes and flooded shores as well as floating bogs (Robert, 1944). The typical habitat is doubtless the last-named, the typical sphagnum bog pond or muskeg pool. The flight season is apparently a rather late one, but our records are scanty, although they come from an immense area. Our earliest record is from Big Piskwamish (about 40 miles south of Fort Albany, James Bay) and is dated July 2, an earlier date than any from more southern latitudes. Omitting this date we have the following range of dates from the various provinces and the Northwest Territory, all of which we consider too scanty to be adequate: Newfoundland, August 30; Nova Scotia, September 2 (one record); Quebec, July 12-September 10; Ontario, July 7-September 11; Manitoba, July 7 to September 9; British Columbia, August 12-26 (estimated by Whitehouse as early July into September); Mackenzie, July 14r-August 21. It thus appears probable that the flight period of subarctica extends from early July to near the middle of September throughout most of this species' range. Nothing is known of the opposition of subarctica except the observation of Robert (1944) that its habits in this regard are similar to those of A. canadensis. Aeshna sitchensis Hagen, (PI. 16: 3; pi. 18: 1, 10; pi. 22: 1, 2; pi. 23: 4; pi. 27: 2) Aeschna sitchensis Hagen, Syn. Neur. N. Amer., p. 119,1861. Aeshna sitchensis Williamson, Ohio Nat., 7: 150,1907. A small northern species with a pale zig-zag mark on the side of the thorax, and a T-spot with a crescentic base.

FAMILY AESHNIDAE

91

Male. Labium pale yellow, distally reddish brown; face pale greenish, paler along the eye margins; labrum edged above and below with black, anteclypeus brown; frontoclypeal suture with a black line; T-spot heavy, with a crescentic base arising from the ante-ocular bar and directed forward; vertex pale yellow with a black border including the ocelli; occiput greenish yellow; rear of head black. Thorax dull olivaceous, not very hairy, grayish beneath; dorsal stripes reduced to small narrow pale spots, sometimes apparently absent; first lateral stripe pale yellowish, passing into bluish behind and above, narrow and sinuate, or twice bent at alternate angles, widest in front and at the first bend, this section adjoining the mesopleural suture, on the anterior side of which is a pale episternal spot; upper and hind part of the first stripe linear and curved upward; second stripe narrow and somewhat T-shaped; between the two stripes is a narrow sinuate pale streak, interalar tubercles apparently pale yellowish. Legs reddish brown, femora nearly black beneath. Wings hyaline, costal margins brown, pt. long, dark brown, yellowish beneath, membranule uniformly smoky brown. Abdomen with segs. 1 and 2 brown, spots chiefly blue above, bluish or green on the sides; 3-10 brownish black with the usual pattern or blue spots, which are slightly larger than usual, MD greenish or yellowish, triangular to transverse on 4-8, somewhat quadrate on 3, on which it is broadly confluent with ML. Eyes short, their line of contact not more than one-half longer than the occiput, sometimes no longer than the latter. Abdomen without a tubercle on seg. 1, auricles usually with 3 teeth; spines of ant. lamina stout at base, extending caudad well behind the hamuli, distally curving downward and tapering to slender, pointed apices; hamular processes very large, triangular with mesal edges contiguous, bases broadly rounded, apices acute; hamular folds small, close together, more or less concealed by the processes, with which they are connected by a low ridge. Sup. apps. about as long as 9 + 10» similar to those of juncea but in profile straight, scarcely elevated even distally, except the superior carina, which is somewhat raised above the level of the lateral margin towards the apex, bearing 8 or 10 minute denticles on the apical third, apices bluntly angulate, abruptly decurved and .ending in a small spine. Female similar to male in markings with the usual differences, the more notable of which are the considerably smaller size of the PD spots of the abdomen and the somewhat larger lateral spots. Some individuals are entirely heterochromatic, the pale markings being all yellowish green, whereas some are at least partly, if not entirely, homoeochromatic. Genital valves barely longer than dorsum of 9; their lateral carinae percurrent, prominent, their ventral surfaces steeply declivent and distinctly grooved; styli (.6 mm.) about half as long as dorsum of 10; basal plate of ovipositor with posterior margin straight or obscurely bilobed. Anal apps. about as long as 9 -f- 10, lanceolate with margins about equally convex, greatest width at middle about one-fourth of the length, apices angulate with a small terminal tooth. Anx 16-18/10-11; pnx 10-13/11-15; h. w. with 5 paranal cells; anal triangle 2-celled; I R3 forking under proximal end of pt. or the first postnodal cell before it, in the hind wing occasionally opposite to second cell before it; the fork distinct but the upper branch comes off at a much greater angle than the lower branch; 2-3 rows of cells between forks at level of distal enaof pt.; 2 rows of cells between R3 and I R3 for considerable distance before and after the point of forking; 4-5 rows of cells between I R3 and Rspl at level of widest separation. Measurements. Total length $ 57-60, $ 57.0-58.5, abd. $ 40.0-44.5, $ 38.5-40.0; h. w. $ 38.0-40.5, $ 36.5-40.0; h. f. 3 7-8, $ 7.0-7.3; w. hd. 3 $ 6.4-7.0, pt. $ 3.4-4.0/3.5-4.2, $ 4.5-5.0/4.5-5.0. Nymph (pi. 31: 4; pi. 33: 4). Small and slender, head as in juncea and interrupta, widest about middle of eyes; which are slightly more prominent than in juncea; lateral margins short, passing through well-rounded angles into the hind margin, which is straight or only feebly concave; antennae 6-segmented, folded labium reaching middle of mesocoxae, relatively wide in proximal half, with sides nearly straight and slightly

PLATE 12

Wings of Gomphidae (1, 2) and Cordulegastridae (3): (1) Hagenius brevistylus; (2) Gomphus (Gomphurus) fraternus; (3) Cordulegaster diastatops.

FAMILY AESHNIDAE

93

divergent, distally strongly convex, the greatest width well before the palpal articulations, about equal to four-fifths of the length of the prementum; proximal width of which is barely less than two-thirds of its distal width; ligula prominent, narrow and obtusangulate, very like that of juncea; palpal lobes not tapering, their distal margins parallel and close together, the distolateral angles barely rounded, their distomesal angles greater than a right angle, with a minute end-hook. Supracoxal processes rather short and blunt, subequal in length, the posterior process slightly the stouter, interval nearly rectangular. Abdomen broadest at 6 and 7 a little more slender than in most species; lateral spines on 7-9 only, those of 7 minute, those of 8 extending halfway to base of 9, those of 9 as far as proximal fourth of 10. Paraprocts scarcely longer than 9 + 10, their apices incurved; epiproct about one-fourth shorter; cerci about half as long as paraprocts; ovipositor extending over 9 and about a fourth or third of 10, the genital valves a little shorter. Head (exuv.) almost uniformly brownish, thorax with traces of paler mottlings in some specimens. Legs nearly uniform, with traces of two or three pale femoral annuli, a median, an ante-apical and sometimes a basal annulus. Abdomen brownish with pale markings almost exactly as in eremita and interrupta. Extending almost the entire length is an ill-defined brown median stripe, which tends to deepen in front of the dorsal puncta, typically forming paired submedian A-shaped spots at trie front margins of most of the segments. This stripe is bordered laterally by a pair of pale stripes, which are most distinct on the front segments and the front part of each segment, forming in dark specimens a subcontinuous series of pale spots. Laterad of these stripes is a series of subcrescentic spots and a broad marginal pale area, just enclosing the lateral scars, which are outlined in brown. Puncta all dark brown. Length 30-37, abd. 21-25, h. w. 6.3-7.2; h. f. 5.2-6.0; w. hd. 6.&-7.2; w. abd. 5.5-6.5.

Habitat and range. Muskeg pools or cold sphagnum ponds, Nfld. and Labr., to Hudson's Bay and Alaska, s. to Me., the lower St. Lawrence, n. shore of Lake Huron, Isle Royale, Mich., Duluth, Minn., s. Man., Banff, Alta., Field and n. Vancouver, B.C. Distribution in Canada and Alaska. Nfld.—Bay of Islands, St. John's. Labr.: Hopedale. Que.—Magdalen Is., Thunder River, Trinity Bay and Anticosti I., Isle of Orleans, Levis, Mt. Tremblant; La Ferine, Abitibi Co.; Rupert House and Great Whale River, James Bay. Ont.—Simcoe Co. (1 stray), Algoma, Cochrane, Thunder Bay and Kenora (Patricia section) districts, n. to Ft. Severn. Man.—Winnipeg; Victoria Beach; Winnipeg Beach; Husavick; and Treesbank in s. Manitoba; The Pas, Lake Atikameg, Gillam and Churchill in n. Man. Sask.—Lac Vert; Crean Lake. AZto.—Banff, Nordegg. B.C.—Field; Mt. Robson; Jesmond; Queen Charlotte Is.; Prince Rupert; Atlin. N.W.T.-Mackenzie Dist: Ft. Smith; Ft. Resolution; Gros Cap, Caribou and Outpost Is., and other stations on Great Slave Lake; Norman Wells. Alaska—Sitka (type locality); Burroughs Bay; Juneau; Palmer.

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THE ODONATA OF CANADA AND ALASKA

Field notes. This is a truly boreal species, which is at home in the muskeg ponds of the north. Our first discovery of it in numbers was on a clearing on the slope of Sulphur Mt, Banff, Alta., at an altitude of about 5,000 feet. This was on June 29, 1913, and all the individuals seen were semi-teneral, this flight being probably their first from their breeding place, which we failed to find, although we examined a variety of ponds, lakes and streams. Eight years passed before we met with A. sitchensis again, and even then we spent two weeks in July at Banff without findng a trace of our quarry. Returning to the Rockies on August 5, however, we found sitchensis first at Field, B.C., and then a few days later at Banff. The spot at Field was a small mossy bog at the foot of a mountain and fed by die seepage from a cold mountain brook. There were only a few puddles of open water in this bog and no true aquatic vegetation, either floating or standing. Only one other species of dragonfly was here, Somatochlora franklini Selys. Females of both were ovipositing. The males of A. sitchensis flew low, as a rule only a foot or two above the bog, sometimes apparently flying at random, sometimes following the stream for a short distance but not covering a definite beat. Females were frequently observed ovipositing in the wet moss about the edges of the small puddles in the bog. The manner of oviposition was like that of most aeshnas. The insect would light on the moss and thrust the abdomen into it in various directions, following no regular pattern. Usually she remained at one spot less than half a minute; then, flying on a few yards, she repeated the operation. Once or twice copulating pairs were seen to rise from the bog and fly to the neighbouring trees. The other bog, which we visited on August 9, was at the foot of Mt. Rundle, Banff, and was similar to the one at Field but much larger, with two or three small ponds, around which Typha and other standing aquatic plants grew. But the water was too cold for dragonflies here. The upper and middle parts of the bog were mossy and practically without standing aquatics, and the open areas of water were mere puddles like those at Field. The water in these puddles was also warmer. We soon observed Aeshna sitchensis flying and ovipositing as before and soon afterwards a Somatochlora was seen and captured. It was not, however, franklini but at the time a new species later described as whitehousei. Prolonged search for exuviae of Aeshna sitchensis was finally rewarded by a fair series, as well as a full-grown nymph. In 1926 we found A. sitchensis at Prince Rupert, B.C., about the bog ponds described under Aeshna juncea. Many exuviae were found here during June, the season of emergence being probably a little earlier here than at Banff. The ponds here are stagnant with a soft, muddy bottom, and only an inch or two of clear water. The adults of A. sitchensis have been carefully observed by Whitehouse (1941) at Massett, Queen Charlotte Islands. When he arrived there on

FAMILY AESHNIDAE

95

July 17, "A. sitchensis, newly emerged, was the common dragonfly and the only species of its genus then on the wing. For a period of two weeks both on the roadways at sea level and on the upland muskegs, I had opportunity of observing these insects and their choice of resting places. TTiese were invariably tree trunks, living or fallen, planks in the roadway or the sand in between, and, on the muskeg, twigs of dead bushes; never green vegetation on either tree or bush. My notes from the Queen Charlotte Islands respecting sitchensis include the statement that they were Very tame/ and I now recollect that I amused myself upon occasion by plucking them from their resting places with my fingers." The ranges of dates gathered into regions, omitting those with only two or three records, are as follows: Quebec, June 4-Sept. 10; Ontario, June 25Sept. 14; Manitoba and Saskatchewan, June 12-Sept. 6; British Columbia, June 16-Aug. 21; N.W.T., June 2&-Aug. 28. The average flight period appears thus to be from about the third week in June to the first or second week in September. Aeshna septentrionalis Burmeister. (PL 16: 4; pi. 18: 2, 11; pi. 22: 3, 4; pi. 27:1) Aeschna septentrionalis Burmeister, Handb. Ent, 2: 839,1839. Aeshna septentrionalis Calvert, Occas. Papers Boston Soc. Nat. Hist., no. 7, p. 23,1905. Aeshna caerulea septentrionalis Walker, Can. Ent., 40: 386, 390, 451,1908. A small subarctic species, a little more robust than sitchensis, the T-spot without a crescentic base, blue of abdomen very extensive. Labium dull yellow, stained peripherally with brown, labrum greenish yellow, edged above and below with black or brown; anteclypeus brown, face otherwise olivaceous, paler next to the eyes, fronto-clypeal suture with a heavy black line; T-spot with heavy cross-bar and short stem, which may be obliterated by union with the base, which has no forwardly turned spurs; vertex light yellow, margined behind with black, occiput yellow; rear of head black. Thorax dull grayish olivaceous, very hairy; darkened along the sutures and about the lateral stripes; dorsal stripes reduced to a pair of minute elongate pale spots; a pale streak usually present along the lower half of the mesopleural suture in front. Lateral stripes pale greenish, probably bluish above; first stripe Z-shaped, widest at lower bend, which is rectangular, upper bend curved and linear. Second lateral stripe nearly straight, obliquely T-shaped; two small pale spots generally present between the lateral stripes. Legs reddish brown, tarsi, distal ends of tibiae ana undersides of femora darkened. Wings hyaline, costal margins and pt. brown. Abdomen brownish black, spots mostly blue, except on sides of 1 and 2, which are pale yellowish to bluish, nearly all the pale spots on segs. 3-10 large and more or less confluent, most of the segments appearing to be blue marked with black rather than the reverse; AML covering most of the sides of 2 back to the transverse carina, connected with, or narrowly separated from, MD; PD on each side of 2 confluent with PL and with the opposite member of its pair. ML on 3 to 6 frequently confluent with PL, MD very large, semielliptical or subquadrate and generally broadly connate with ML, except on 8, on which it is reduced; generally confluent with PD on some or all of the segments, PD pairs narrowly divided; spots on 10 connate.

96

THE ODONATA OF CANADA AND ALASKA

Eyes small, the line of contact less than 1 mm. long, about as long as the occiput, vertex larger than in sitchensis, twice as broad as long; occiput broader than long. Thorax and abdomen somewhat more robust than in A. sitchensis. Spines of ant. lamina rather stout, shorter than in sitchensis, straight and blunt; hamular processes similar to those of sitchensis but with the apices more rounded; hamular folds very small, often concealed in direct view. Sup. apps. a little shorter than 9 + 10, broader than in sitchensis with rounded apices, the mesal margins of the broad distal portions slightly convex; basal fifth rather slender and somewhat bowed; lat. margins viewed in profile curved upward in distal half, the sup. carina elevated and arcuate in the distal fourth, bearing a few irregular granules or denticles, ventral carina moderately prominent, convexly curved; inf. app. not quite half as long as sup. apps., basal width three-fifths to two-thirds of length, apex bluntly rounded. Female similar in size and colour-pattern to the male, the dorsal abdominal spots tending to be somewhat smaller, the lateral spots somewhat larger. PL sometimes separate from PD, but confluent with ML on some of the segments. Evidently there is some degree of dichromatism (vide p. 99, Whitehouse re oviposition) but the preservation of colour in the material studied is not good enough to distinguish two types of colour-pattern. Genital valves a little longer than dorsum of 9, their lateral carinae percurrent, sharp and very prominent, space between them suddenly widened a little beyond the base, thence tapering evenly to the narrow pointed apices. Styli somewhat less than half as long as dorsum of 10; hind margin of basal plate nearly straight; ventral surface of 10 deeply cleft by the hind margin. Anal apps. usually slightly longer than dorsa of 9 -j- 10, lanceolate, a little less than four times as long as wide, widest slightly beyond mid-length, apices rounded, without a projecting tooth. Anx 3 13-18/10-11, $ 13-17/9-11; pnx $ 10-14/11-16, $ 10-12/11-13; h. w. with 4-6 paranal cells, and triangle 2-celled; I R3 forking under proximal end of pt. with 2-3 cell rows between the forks, and two rows in the space between R3 and I R3 at the level of the fork, 3—5 cell rows across the greatest width of the Rspl loop; 3—5 cross-veins under pt, excluding brace-vein; cells in triangle 4-5/3-4; cells in spt. 2-4. Measurements. Total length $ 57-63, 9 54-57; abd. $ 37-42, $ 33-38; h. w. lanceolate, acute, widest a little before the middle, the length about five times the width. Anx $ 14-18/9-12, 9 14-19/9-14; pnx $ 6-9/7-9; $ 8-10/7-12; paranal cells of h. w. $ 6-7, $ 7; cells in triangle usually 5-6/4-6, sometimes 3-7/2-4; cells in spt. 3-5/2-5, usually 4/3; cross-veins under pt. 2-3/2-3, rarely 4 in fore or hind wing. Measurements. Total length $ 69-78, $ 68.6-84.0; abd. (excl. apps.) $ 45-50, 9 45-51; h. w. $ 45-50, $ 45.5-52.0; h. f. $ 10.5-12.7, $ 10.0-10.8; w. hd. $ 10.0-12.5, $ 10.0-10.5; pt. $ 5-7/5-7, $ 5.4-6.7/6-7.

FAMILY AESHNIDAE

127

Nymph (pi. 27: 10; pi. 29: 2). Long and slim; in life green marked with brown. Head widest a little behind mid-length of eyes, about four-fifths as long as wide; eyes larger than in Aeshna but not so prominent, their middle width about three-quarters of their length; posterolateral contours short and well rounded, hind margin barely emarginate; antennae 7-segmented, see. 3 decidedly longer than 1 + 2, seg. 4 very short, last 3 segments very slender; folded labium extending rearward well beyond mesocoxae, usually about half-way between coxae 2 and 3; prementum 3 mm. wide at base, expanding distad to 4 mm. in the narrower proximal part then a little more rapidly to distal end, with edges slightly arcuate; width at palpal articulation a little more than twice the basal width; ligula projecting more than in Aeshna, the median cleft correspondingly longer; blades of palpal lobes curving slightly distad and terminating in a hook, the distolateral angle being broadly rounded ana the end-hook well marked. Supracoxal processes very short and blunt, about equal in length and width. Legs rather slender, hind femora about as long as width of head. Abdomen slender at base, widening to seg. 7; 7 and 8 about equal in width; lateral spines on 7-9, somewhat divergent, those on 7 attaining about two-thirds of the distance from base of spine to base of 8. Spines on 8 and 9 about equal in length, those of 8 attaining level of base of 9, dorsal nooks absent. Anal pyramid a little longer than 9 + 10, paraprocts reaching a little beyond epiproct, male projection about a fifth as long as paraproct, truncate; cerci half ( $ ) or slightly more than half ( $ ) as long as paraprocts, with a slender spine-like tip. Rudiment of ovipositor about two-thirds as long as sternum of 9. Colour-pattern sometimes pale and not very distinct, sometimes clearly marked or very dark. Head behind eyes with broad pale margins and a narrower pale stripe on each side mesad of the pale margin. A broad dark stripe extends along each side of the prothorax and mesothorax to the abdomen, where it breaks up into segmentally arranged spots connected with the dark outlines of the lateral muscle-scars. Dorsum of abdomen with a fine median white line, dividing a broad dark stripe, which widens segmentally and is darkest about the dorsal puncta; on each side of the dark stripe is a paler unbroken wavy stripe, followed laterad by an irregular broken series of alternate pale and dark stripes; all the puncta dark. Femora pale brown in proximal half, distally pale with apices and an ante-apical annulus dark; tibiae and tarsi nearly concolorous. Length 43.5-47.0; abd. 29-32; w. abd. 8.5-9.0; h. w. 8.0-9.5; h. f. 8.5-9.5; w. hd. 8.5-9.0.

Habitat and range. Still waters with emergent vegetation, from small semipermanent ponds to lakes, sheltered bays and slow streams. U.S., s. Canada and Alaska; also Mexico, Costa Rica to Panama, West Indies, Bermudas, Hawaiian Is., Tahiti, Kamchatka, China. Distribution in Canada and Alaska. N.S.—Annapolis, Colchester and Pictou counties; P.E.L-(Harley White, July 8, 1944; Needham and Westfall (1955)); N.B.-Hagen, 1890. £we.-Montreal; St. Hyacinthe; Aylmer; Wakefield; Kazabazua. Ont.—Essex, Kent, Elgin, Norfolk, Haldimand, Welland, Huron, Wellington, Peel, York, Dufferin, Durham, Northumberland, Prince Edward, Simcoe, Victoria, Hastings, Frontenac, Leeds, Prescott, Carleton and Renfrew counties; Muskoka, Parry Sound and Thunder Bay districts. Man.—Treesbank (Aweme); Stockton, Kildonan Park (Winnipeg); Victoria Beach; Lake Winnipeg; Husavick. Sask.—Markinch, Buffalo Lake. Alta.— Lethbridge. B.C.—Vancouver I. (Thetis and Florence lakes; Wellington Lakes; Forbes Landing); Squawcum Lake, Harrison Bay, Salmon Arm, Oliver, Osoyoos. Alaska—Sitka; mountains between Mission and Forty-Mile Creek; Eagle City.

PLATE 20 Aeshna—anal appendages of males ( 1-8, odd nos., dorsal; even nos., lateral; 9, 10 dorsolateral): (1, 2) A. eremita; (3, 4) A. i. interrupta; (5, 6) A. i. lineata; (7, 8) A. i. "nevadensis" (lineata); (9) A. i. lineata; (10) A. f. interna; (11) A. i. lineata (lateral).

FAMILY AESHNIDAE

129

Field notes. This is the earliest of all Odonata to appear in the spring in southern Ontario, sometimes arriving in the vicinity of Toronto as early as April 15, although not often seen until some time in May. All spring arrivals are fully mature and, as soon as they arrive they may be seen flying in tandem and ovipositing. No exuviae have been found in April or May, nor have tenerals been reported at this time of the year. The possibility of hibernation of the adults, suggested by Whedon (1914) is thus precluded and there seems to be no doubt that these early individuals have emerged farther south, probably in the northern United States, although it is also possible that a few of them may emerge in the extreme south of Ontario, for instance on Point Pelee, where large numbers were seen in April 1955, although it was not known whether they were tenerals or not. Images continue to appear, the peak of numbers being reached about the middle of June. In July the population dwindles so that, as the end of the month approaches, they may disappear, although a few old individuals sometimes remain until early August. Before these old individuals of spring and early summer have entirely vanished or sometimes a little later, that is early in August, the main period of emergence begins. This continues throughout August and into the first week or two of September, with adults seen in flight as late as the middle of October. Tenerals sometimes appear in great numbers, drifting about in the sunshine in open fields but never remaining with us long. In fact they do not become mature in any part of Canada, so far as we know, since they have never been seen mating, ovipositing or even with the blue coloration which indicates maturity. Our belief is, therefore, that these individuals fly southward and this belief is supported by statements of various writers who claim to have observed Anax junius in large numbers moving in definite directions. Shannon (1916) refers to this species as the "common Long Island migrant," having frequently observed it in August and September travelling westward along the Connecticut shore of Long Island Sound. He also refers to seasonal flights southward along the coast of New Jersey, on the basis of Wolff's observations at Cape May in September, and to resting swarms at Point Pelee, which he regarded as evidence that Anax also follows the shore of lakes Ontario and Erie. Until the year 1948 we had never found an exuvia before the beginning of August but, on July 15 of that year, we found a single specimen on a cat-tail in the creek near DeGrassi Point, Lake Simcoe. On June 27, 1953, at one of the glacial ponds near Snelgrove, Ont., we found the first exuviae for June, one floating and the other clinging to a stalk of manna grass

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THE ODONATA OF CANADA AND ALASKA

(Glyceria striata). On June 12,1955, and again a week later, we found Anax junius emerging in fair numbers from a shallow gravel pit at DeGrassi Point. Until recent years this pond had been only a very small temporary pool, devoid of any Anax nymphs. Whether these earlier emergences are due to an earlier start on the part of the parental generation the previous year or to a more rapid development than usual of the nymphs in the shallow sunwarmed gravel ponds, we are unable to say. Calvert (1934), who reared one Anax junius from egg to adult and many others part way through their larval period, found that the embryonal period varied from eight to nineteen days, although this does not necessarily represent the total range of variation of the period. There were 13 instars and the period of larval development was 315 days. During this period the winter diapause occurred between October 17 and March 20 but, as the nymph was kept at room temperature, the diapause may have been somewhat shortened. In any case there could be only one generation annually. It is thus apparent that the individuals that emerge in August and September are not the progeny of those that arrive in the spring of the same year but probably of those of the preceding spring. This indicates a somewhat longer developmental period, which is due in part at least to a longer diapause. At the time of mating there is a wild nuptial flight rarely seen in Canada, since on arrival here the females are already engaged in ovipositing, usually in tandem, although single ovipositing females are not infrequent. Generally the pair flies back and forth over the water on the shore, dropping now and then to some collection of dead floating plants, such as pieces of last year's Typha and, resting in a horizontal position, the female submerges her abdomen to various depths and inserts her eggs into this material. The pair remains but a fraction of a minute, then rising again and flying to another spot to repeat the process. We have also seen pairs ovipositing in floating logs, probably somewhat decayed, in a floating water-lily leaf, in a bed of tangled pondweed (Potamogeton sp.), or, late in the season, the living stems of Typha. Emergence usually takes place early in the morning, but at the gravel pit pond mentioned above, in June, 1955, we saw a number of individuals just emerged or in the act of emergence late in the forenoon, and in the afternoon. The sky,'however, was somewhat overcast. Anax junius is an extremely active species and in fine weather may be seen on the wing from early morning until dusk. According to Williamson (1899), "Occasionally this species will appear in large compact flocks which pass back and forth in pursuit of insects, very much after the manner of night hawks. Like this bird, too, as twilight comes on, they fly nearer and nearer the ground as the flocks of small diptera settle to the earth." In Canada Anax junius is abundant only in the southern parts of the eastern provinces. Whitehouse (1941) says: "This species is far from common in western Canada, in fact I collected dragonflies in Alberta and British

FAMILY PETALURIDAE

131

Columbia for twenty years before seeing one." He finally obtained unquestionable evidence of their breeding in British Columbia. This was at Squawcum Lake, Harrison Bay, August 15-19, 1936. Recently emerged males and females were found in numbers, as many as ten having been seen in the air at one time. This is the time of the year when tenerals are most common in southern Ontario. FAMILY PETALURIDAE NEEDHAM

These are large robust dragonflies, found in a few limited and widely separated geographical regions, their pattern of distribution combined with their archaic structure affording convincing evidence that they are the remnants of an earlier fauna, which was formerly much more widely disr tributed. This view gains further support by the occurrence of fossils of this family in the lithographic slate beds of Upper Jurassic age at Solenhofen, Bavaria (Handlirsch, 1908). The adults possess a mixture of gomphid, aeshnid and cordulegastrid characters, with a hint of the libelluloid families. The eyes are about as widely separated as in the Gomphidae, but the occipital ridge is not a sharp crest but is rounded as in the Cordulegastridae. The median lobe of the labium is cleft as in the latter family, but the forelegs of the males lack any trace of the tibial keels, vestiges of which are present in the Cordulegastridae and Gomphidae (St. Quentin, 1938). The abdomen is subcylindrical, as in the Aeshnidae, with no terminal enlargement. The anal appendages of the males are short and the inferior appendage is broadly bifurcate, recalling the Gomphidae except in its greater median length. The superior appendages, however, despite their shortness, have more of the spatulate form found in the Aeshnidae. The ovipositor is complete and essentially like that of the Aeshnidae, although very small, with die styli lacking the terminal tuft of hairs or single seta. The venation, although resembling that of all other families, has features of its own. The sectors of the arculus are well apart at base; the triangles of both pairs of wings are about equidistant from the arculus of their respective wings and not greatly elongated on either front or hind wings. In the North American genera Tachopteryx and Tanypteryx (the latter represented also in Japan), the triangles are much alike in the two wings, the elongation, if any, being in the long axis of the wing, but in the Australian genus Petalura the triangle of the fore wing is somewhat elongated transversely, that of the hind wing longitudinally, and this feature with the reticulated subtriangle in the fore wing only, is one of the libelluloid characters mentioned above (Tillyard, 1917). The division of the fore subtriangle into three cells is a common but not universal feature, since, in the only Canadian species, Tanypteryx hageni (Selys), it may be merely crossed or even clear. The subtriangle of the hind wing is simple and clear. There is little or no development of radial or median supplements. The extremely long pterostigma, covering more than a fourth of the distance from the nodus to the tip of R!

PLATE 21

Aeshna—anal appendages of males (odd nos., dorsal; even nos., lateral): (1, 2) A. verticalis; (3, 4) A. canadensis; (5, 6) A. clepsydra; (7, 8) A. tuberculífera; (9, 10) A. júncea; (11, 12) A. subarctica.

FAMILY PETALUKDDAE

133

and surmounting from five to nine cells is a noteworthy archaic feature. The presence of a brace-vein at the proximal end of the pterostigma is another gomphid and aeshnid character. The nymphs have been well described as rough-hewn, the stout carinated legs and angulate lateral margins of the abdominal segments giving them this appearance. The small eyes, capping the front angles of the head, and the somewhat elongate, subcylindrical body is suggestive of Cordulegaster, but the flat labium, lacking premental setae, and the relatively narrow, though somewhat concave, palpal lobes, also without setae, show a greater resemblance to the Gomphidae and Aeshnidae. Probably the most distinctive character is the spur at the base of the movable hook. The antennae are seven-segmented, the segments all short and about as wide as long. The legs are also generalized, showing little or no trace of gomphid specialization, the tarsi being all three-segmented and the three pairs essentially alike. The Petaluridae are inhabitants chiefly of mountain swamps, and the nymphs of some of the species actually burrow in the mud or peat in a manner suggesting the burrowing crayfishes (Williamson, 1932). Tillyard (1917) illustrates the nymph of the Australian Petalura gigantea in the act of emerging from the soil prior to its final transformation. Two closely related genera are described from North America, Tachopteryx and Tanypteryx. Tachopteryx is monotypic, the single species, T. thoreyi (Hagen) being rather widely distributed in the eastern United States, whereas Tanypteryx is represented by two species, T. hageni in the mountains of the western United States and southern British Columbia and T. pryeri in Japan. The nymphs of Tachopteryx thoreyi and Tanypteryx pryeri have been described. Since T. thoreyi has been found in Michigan near Detroit its occurrence in southern Ontario is by no means improbable. We therefore include the genus in the following key. KEY TO THE GENERA OF PETALURIDAE ADULTS Ventral side of metathorax (intersternum) with a large hairy tubercle; primary antenodal cross-veins consisting of the first with the third, fourth or rarely fifth; anal loop with 2 to 4 cells; thorax black marked above and on the sides with yellow Tanypteryx Ventral side of metathorax without a tubercle; primary antenodals

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THE ODONATA OF CANADA AND ALASKA

consisting of the first with the sixth or seventh; anal loop with 5 to 7 cells; thorax gray above and on the sides, with 2 oblique black lateral stripes Tachopteryx NYMPHS* Antennae 6-segmented, the third and fifth segments each longer than wide; cerci each more than half as long as epiproct Tanypteryx Antennae 7-segmented, the third to fifth segments each wider than long; cerci each less than half as long as epiproct Tachopteryx Genus Tanypteryx Kennedy Proc. U.S. Nat. Mus., 52: 507, 1917. Type species Tachopteryx hageni Selys This genus is very close to Tachopteryx, the presence of the hairy tubercle on the intersternum being the principal difference. Kennedy states that the subtriangle of the fore wings is "three-celled, its sides subequal" That this is not always true is indicated under the heading of T. hageni. The venation in general is not as close as in Tachopteryx (Kennedy, 1917). In colour-pattern Tanypteryx is black with yellow or orange spots, whereas in Tachopteryx the ground colour is largely gray and the abdomen ringed rather than spotted with yellow. The nymph of T. pryeri of Japan has been described by Asahina and Okumura (1949). Their figure is very like Williamson's figure of Tachopteryx thoreyi but differs in some details of the antennae and labium. The antennal differences have been given in the key. The prementum of the labium in both genera is fully as broad as long. The ligula in Tanypteryx is scarcely produced at all and has a very small median cleft; that of Tachopteryx, on the other hand, is distinctly produced and rounded and the cleft is represented as more than a fourth as long as the prementum. The palpal lobes although somewhat curved are flat and without palpal setae. They are distally truncate and the distal and mesal edges are minutely and irregularly crenulate. There is no end-hook but a well-developed movable hook, which is, however, relatively short compared with those of our native Gomphidae and Aeshnidae. Tanypteryx hageni (Selys). (PL 2; pi. 27: 8, 9) Tachopteryx hageni Selys, C. R. Soc. Ent. Belg., 22: 68,1879. Tanypteryx hageni Kennedy, Proc. U.S. Nat. Mus., 52: 508,1917. Male. Labium dark olivaceous; mandibles, labrum and clypeus dark brown; frons pale yellow; vertex black; occiput dark with a pair of pale yellow spots on the posterior slope. Prothorax with a pair of widely separated dorsal yellow spots; pterothorax black, dorsum with a pair of large yellow spots in front and small ones behind; mesopleura and metapleura each with two yellow spots, the smaller above; legs black; wings *After Gloyd.

FAMILY GOMPHIDAE

135

colourless. Abd. segs. 2-8 with paired orange spots on the anterior half, most of the pairs separated by a roundish black space in front but becoming contiguous behind; segs. 8 and 10 and anal apps. black. Female. Similar in size and colour-pattern, except that the yellow abdominal spots are larger and closer together, giving die effect of cross-bands rather than spots. Pt of fore wings slightly shorter than those of hind wings subtending, f. w. 4 or 5 cells, h. w. 5 or 6 cells; triangles of fore and hind wings nearly alike, scarcely if at all elongate; those of fore wings crossed, those of hind wings clear; subtriangie of fore wings usually divided into two or three cells, sometimes clear; those of hind wings small and clear. Primary antenodal cross-veins usually the first and fifth of the fore wings, first and fourth of hind wings; anal loop of four or five cells. Anx 13-15/8-10; pnx 9-10/5-7. Measurements. Total length $ 55-59, 9 53-55; abd. £ 38-42, 9 39; h. w. 3 34-37, 9 35^37; h. f. $ 7.0-7.5, 9 6.5-7.0; pt * 4.5-5.2/5.3-6.0, 9 5.2-5.5/6.0-6.5. Nymph unknown, probably very similar to that of T. pryeri of Japan, the only other known species of Tanypteryx (see under Tanypteryx).

Habitat and range. Probably high mountain swamps. Calif, and Nev. to Wash, and s. B.C. Distribution in Canada. B.C.—Liumchin Creek, near Cultus Lake, Chilliwack dist, July 8, 1934; Yale, Fraser River, vicinity of Hell's Gate, August 30,1938. Field notes. Nothing is known about the habits of this insect, except that it is found in woods at high elevations, its occurrence at low levels being accidental. FAMILY GOMPHIDAE RAMBUH

Inst. Neur., p. 152,1842 (as subfamily of Aeshnidae). The Gomphidae are a family of usually medium-sized dragonflies of distinctive appearance and habits. The widely separated eyes and clear wings, the more or less cobra-like expansion of the terminal segments, particularly in the males, the black or brown and green coloration of nearly all of our species and the habit of taking short flights and coming to rest on the ground or on low vegetation, all combine to leave a characteristic impression on the mind of the observer. The eyes are well separated, the vertex being thus widely connected with the occiput, although a transverse occipital suture separates them. On the vertex behind the ocelli is a transverse ridge, the postocellar ridge, which tends to crowd the ocelli into a straight transverse row. The nearly equal size of the three ocelli is another peculiarity of the family. In females there is frequently a pair of spines or horn-like processes arising from the lateral ends of the post-ocellar ridge or in their vicinity. The occiput is usually a flat plate, tilted upwards and ending in a sharp crest, which bears a transverse fringe of hairs. In some cases, however, the posterior margin is abruptly bent upward, in others it is thick and rounded. These variations are most marked in the females, in which they provide useful systematic

PLATE 22

Aeshna—anal appendages of males: (1, 2) A. sitchensis, dorsal and lateral; (3, 4) A. septentrionalis, dorsal and lateral; (5) A. constricta, lateral; (6) A. umbrosa, lateral; (7) A. palmata, lateral; (8, 9) A. califarnica, dorsal and lateral; (10, 11) A. multicolor, dorsal and lateral; ( 12, 13 ) A. mutata, dorsal and lateral.

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characters. The middle lobe of the labium is entire. The legs are relatively sturdy. The fore and middle femora are a little longer than their associated tibiae, whereas the hind femora are considerably longer than the hind tibiae. There are usually numerous short spines on the ventral and lateral surfaces of the femora, although the median region on which the tibia is flexed remains free from spines, particularly towards the femoro-tibial articulation. In Dromogomphus the hind femora bear a series of long ventral spines in addition to the usual short ones. The femora sometimes bear also minute dorsal spines in longitudinal series. The tibiae bear several rows of spines, all minute except the ventral series, which are stout but not very long. In addition to the usual comb the fore tibiae of all our native Gomphidae, except Hagenius, bear each a vestigial tibial keel (pi. 5: 2, 3). The tarsal segments are armed ventrally with short, close-set spines. The tarsal claws (pi. 5: 8) are like those of the Aeshnidae, each bearing two widely separated hooks, a terminal one and a ventral one, the latter usually the smaller. The venation is, on the whole, rather primitive. The triangles are about equidistant from the arculus and are rather short, those of the fore wings being often nearly equilateral, whereas those of the hind wing are somewhat elongated in the long axis of the wing. Subtriangles are present in all the wings and in the genera of our fauna, except Hagenius, are normally clear. The median space is free and the cubital space has two cross-veins only. There is usually no anal loop; when present it is small and compact and has no midrib. The anal border of the hind wing is strongly angulate in the male, in which the anal triangle is also well developed. The pterostigmata have an oblique brace-vein and are usually fairly long. Radial and median supplements are not developed and the trigonal supplement is absent in our genera, except Hagenius. The membranule is very small or absent. The abdominal segments are subcylindrical from the base to the sixth segment but segments 7 to 9 are usually more or less enlarged, the terga being more broadly arched than in the more anterior segments and ventrolaterally produced, with corresponding widening of the sterna. Segment 10 is typically small. The ovipositor is reduced to a bifid vulvar lamina, arising from the sternum of segment 8 but extending over the ventral surface of segment 9. It varies greatly in length and form, being sometimes flat, sometimes arched.

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THE ODONATA OF CANADA AND ALASKA

The bifurcation may extend nearly to the base or it may be little more than a deep notch. The anal appendages of the male are usually no longer than segment 10, although there are marked exceptions in various exotic genera. They vary greatly in form and offer some of the best specific characters. The significance of the small size of the anal appendages as compared with those of the Aeshnidae is apparent when a pair in copula is observed. Only the rear part of the female's head, particularly the occiput, is grasped by the male's anal appendages. The superior pair is applied to the rear of the female's head, as the upper jaw of the vise, while the inferior appendage of the male is applied to the dorsal side of the female's head, forming the lower jaw. Thus the superior appendages tend to remain simple and convex above but ridged and toothed below, whereas the inferior appendage is remarkably broad and divaricate, the undivided base being short in comparison with that of the Petaluridae, Aeshnidae and Cordulegastridae. The male genitalia are fairly generalized. Both pairs of hamules are present and typically functional, although the anterior hamules are smaller than the posterior pair and sometimes vestigial. Generally both pairs are modified in various ways as claspers. They are frequently hooked or bifid. The guard is without a carina. Auricles are present on the sides of the second abdominal segment. The penis of the Gomphidae, which was studied by Fraser (1940) to determine its taxonomic value for the family as a whole, has not been used in the present study except in the genus Gomphus, in which it was found to be of exceptional value. The enlarged basal segment, commonly known as the vesicle, has never been known to contain sperm capsules, as stated by Tillyard (1917) and repeated in Volume I of the present study. Fraser regards it as an erectile organ and Needham (1948) states that it is filled with muscle fibres and proposes the term peduncle in place of vesicle to avoid any suggestion as to its function. He also employs the term hood for the saccular part of this organ, which arises from the broad base of the peduncle and is very variable in form (vide p. 138). As the term vesicle is well known and is not restricted to the seminal structure of that name, we shall continue to use it, together with Needham's term hood for the saccular part. The second segment of the penis (first—Fraser) is known as the stem, a somewhat C-shaped tube with a strongly sclerotized convex wall and connected with the vesicle by a ginglymus joint (Fraser). The stem is followed by the median segment, whose "dorsal" or exposed wall is also strongly sclerotized. It is strongly bent distad at the proximal joint and leads to the terminal segment or glans, which is partly sclerotized but largely membranous, and very frequently terminates in two flagella, which are often so closely apposed as to appear like a single filament. Beneath the glans there is usually a semimembranous process, the prepuce, generally spoon-shaped

FAMILY GOMPHJDAE

139

and compressed, but sometimes slender and spinelike. There are also frequently lateral membranous preputial folds. The penis has apparently no terminal opening but can be extended by pressure from behind, like the larval labium. The sperm capsules are liberated into the genital fossa of the female, the penis serving merely as a "swab to transfer sperm capsules from the genital fossa to the female vagina" (Fraser, 1940). The glans and associated structures are the most variable parts of the penis. The glans proper is generally a short, semimembranous, trowel-shaped structure, open above and bearing at the posterior angle a slender needlelike process, but often a pair of long, curved or coiled, flexible filaments, which may be partly covered by a dorsal sheath formed by a prolongation of the collar-like pair of sclerites arising immediately before the glans. Other variations will be described under the genus Gomphus, in which the penis is a structure of great taxonomic value. Returning to the vesicle, we may now note that the two main types of penes are generally associated with the two main variations in the form of the vesicle, but not always. Whatever its main function may be, the vesicle, or more specifically the hood, serves also as a sheath for the protection of the delicate terminal parts of the penis. Its anterior wall is invaginated along the middle line, the fold extending to a greater or less extent along the dorsal wall (in the natural position actually the ventral wall). Those species which have a short glans and lack the long filaments are usually associated with the split-loaf type of vesicle (Needham, 1948), in which the fold is mainly anterior and die body of the vesicle is convex and often prolonged caudad. In species with the elongated glans and usually paired filaments, the infolding of the wall is carried much farther caudad, usually along the whole length of the vesicle to the anterior end, and the lateral walls of the imagination extend outwards like a pair of flaps, while the general form becomes more or less pyramidal, the posterior wall in profile appearing to be straight or concave instead of convex. This type of vesicle is termed by Needham the cleft-pyramidal type. In its more extreme form the walls of the sheath are very hairy. Between the extremes of the two types there are various forms (v. Gomphus). The colour-pattern in our native species is not particularly variable. Our Gomphidae are nearly always green or greenish yellow marked with black or brown or, when the dark colour predominates, they appear to be black or brown marked with green. For convenience in description the dark thoracic stripes (pi. 40: 10,11) are numbered and may be briefly described as follows: (1) The first pair of stripes is the mid-dorsal thoracic pair, commonly separated only by the median carina, this being often marked along part or all of its length with green or yellow. These stripes frequently appear as a single broad median stripe.

PLATE 23

Aeshna—anal appendages of females, ventral view: (1) A. eremita; (2) A. interrupta; (3) A. clepsydra; (4) A. sitchensis; (5) A. júncea; (6) A. subarctica.

FAMILY GOMPfflDAE

141

The other stripes may be described for each side as follows: (2) The antehumeral stripe is immediately in front of the mesopleural suture, with which it is more or less parallel. (3) The first lateral or humeral stripe overlies the mesopleural suture and is often partly divided along this suture. (4) The second lateral or interpleural stripe is usually narrow and occupies the interpleural suture, but frequently the only part present is below the metaspiracle and for a short distance above it. Connected with this stripe is often another stripe that follows the suture outlining the metinfraepisternum above. (5) The third lateral or metapleural stripe, which is often absent, overlies the metapleural suture. It is often continuous with a stripe surrounding the base of the hind coxae. Besides the above longitudinal stripes there is a transverse ridge at the front of the pterothoracic dorsum, which is termed the collar (or mesothoracic collar) and is usually conspicuous because of its green or yellow colour. This is known as the collar stripe. It may be isolated or connected with the similarly coloured median carina or the two longitudinal pale dorsal stripes. The posterior part of the median carina and the ante-alar carinae are nearly always dark, whereas the ante-alar sinuses may be pale. The legs are usually black, often striped lengthwise with yellow or green, the wings are hyaline and without spots, except the pterostigmata. The abdomen is chiefly black or brown with a pattern of pale spots, which typically consists of a mid-dorsal segmental series of basal green or yellow spots and a ventrolateral series of similarly coloured spots, beginning with larger blotches on the first two or three segments, then usually smaller ones on the middle segments and finally larger spots on the expanded segments of the club. The nymphs of Gomphidae are more or less flattened, sprawling creatures with the legs wide apart and the abdomen usually elongate. The head is small and the eyes not prominent; the antennae are four-segmented, the third segment much enlarged and often spatulate or discoidal, whereas the fourth segment is vestigial. The prementum of the labium is short and flat, the ligula entire and very little produced, sometimes in fact having no real existence as a lobe, although the margin always bears a fringe of scurry, brown piliform setae. The palpal lobes bear a long moveable hook, but the blade is short, with a toothed or crenulate mesal margin and terminates in a recurved end-hook, or the distal end is merely rounded off. Neither premental nor palpal setae are present.

142

THE ODONATA OF CANADA AND ALASKA

The fore and middle legs are much shorter than the hind legs and are generally modified for shallow burrowing. The femora of these pairs are typically short, stout and curved, and bear dorsolateral and ventrolateral fringes of hair. The corresponding tibiae appear somewhat twisted, owing to the obliquity of the three longitudinal fringes of hair. In all our genera, except Hagenius, the distal extremity of these tibiae bears laterally a stout process, evidently used in burrowing, and known as a tibial burrowing hook. The first two pairs of tarsi have only two segments. The hind femora are much longer and straighter and the tibiae are correspondingly long. They lack the burrowing hooks and the tarsi are three-segmented. Of our endemic Gomphidae the genus Hagenius, with one species, is the only member of the family in which the abdomen is discoidal. In all the others it is either ovate or elongate, although there are no remarkable extensions of segments among northern Gomphidae, such as are found in Apht/lla of the southern states, Mexico and the Antilles, in which the tenth segment is produced into a veritable respiratory tube. In most Gomphidae there are small lateral spines on some of the more posterior abdominal segments, usually 6 or 7 to 9, but they do not vary much in length. Dorsal hooks may be present on most of the segments or only one or two of the terminal segments, in which case they are usually vestigial. The anal pyramid is small in comparison with most Anisoptera. The Gomphidae are mainly inhabitants of streams, large and small, but some develop in lakes and others even in marshy ponds. They are local insects, often extremely abundant for a short flight period but, on the whole, not very common in Canada, except in the more southerly parts of the eastern provinces. Since they transform on broad and usually more or less horizontal surfaces, their exuviae are more readily found than those of most dragonflies that climb sedges and grasses and are soon blown away by the wind. One often finds great numbers of exuviae but very few adults. The nymphs of a few species barely leave the water when about to emerge, merely crawling out upon the upper side of a water-lily leaf (Nymphaea or Nuphar) or supporting themselves only upon a tangle of green algae, the exuviae being often left in the water. Gomphidae are creatures of the sunshine and are inactive on dull days. None of our species fly in the evening, as do many Aeshnidae and Corduliidae. Although they sometimes fly steadily and patrol the shore line, they are much more frequently seen to fly over short distances, coming to rest after a few seconds and settling on the ground, or on logs, rocks, or occasionally on low vegetation. The females of certain species of Gomphus on hot sunny days fly in a series of loops or U-shaped curves downward and upward. The females oviposit unattended by the males and the usual method is to fly low over the water, tapping the surface with the abdomen at irregular intervals, not rhythmically, as in many Libellulidae. Neither have we observed them ovipositing in one spot, as is often a habit of Libellulidae. Miss

FAMILY GOMPHIDAE

143

jongfield (1953) observed two females of Gomphus vulgatissimus in the ^ew Forest "ovipositing in an unhurried and deliberate manner in the very iquid mud of shallows in the stream. Only a thin layer of water lay over the nud, which consisted of several inches on a bottom of soft sand. The ibdomen was curved under and half submerged. I used the word 'pushed* idvisedly as the motions of the abdomen seemed to denote this and there ivas no question of the eggs being 'stabbed' into the mud." Two subfamilies of Gomphidae are represented in our fauna, the Hageniinae and the Gomphinae. These are separated as follows. Hageniinae. Very large dragonflies with the head relatively small; triangles long and narrow, each with one or two cross-veins, the distal side of each triangle angulate with a supplementary vein springing from the angle, the same side of the triangle concave behind the angle. Nymph with abdomen iiscoidal and very flat, the tibiae without burrowing hooks. Gomphinae. Small to large dragonflies with head of usual size; triangles not elongate, without cross-veins; the distal side not distinctly angulate, nor concave, without a supplementary vein springing from it. Nymph lanceolate or fusiform, not greatly depressed; fore and middle tibiae with burrowing hooks (sometimes very small). There are only two genera of Hageniinae, each with a single species, Hagenius Selys from North America, and Sieboldius Selys from Korea and Japan. KEY TO THE GENERA OF GOMPHIDAE ADULTS 1. Triangles with a cross-vein, each with a supplementary longitudinal vein springing from its distal side; hind femora reaching a little beyond the base of abd. seg. 3; very large insects, generally more than 70 mm. in length Hagenius Triangles clear; without a supplementary longitudinal vein springing from distal side; hind femora usually not reaching beyond middle of seg. 2; smaller insects, rarely 65 mm. in length 2 2. Hind wings with an anal loop of typically 3 cells; inf. app. of male with the two rami separated either by a mere slit with the apices contiguous or by a U-shaped or V-shaped notch; vulvar lamina nearly as long as sternum of seg. 9 Ophiogomphus Hind wings without an anal loop; inf. app. of male with more or less widely separated rami, which are generally divergent; vulvar lamina usually less than half as long as sternum of seg. 9 3 3. Thoracic dorsum mesally pale between broad dorsolateral dark stripes; pt. scarcely 3 times as long as wide and more than twice as wide as the space immediately behind their middle; inf. app. of male with 4 rami Octogomphus Thoracic dorsum mesally dark between pale stripes, pt. more than

PLATE 24

Aeshna—anal appendages of females, ventral view: (1) A. palmata; (2) A. umbrosa; (3) A. constricta; (4) A. tuberculífera; (5) A. multicolor; (6) A. calif ornica.

FAMILY GOMPHIDAE

145

3 times as long as wide and usually less than twice as broad as the space behind their middle; inf. app. of male with only 2 rami 4 4. Pt. less than 4 times as long as wide, more than twice as wide as the space behind their middle; inf. app. of male with its lateral edges subparallel, its two rami shorter than the median length of the appendage; size small (25-40 mm.) Lanthus Pt. rarely less than 4 times as long as wide, less than twice as wide as the space behind their middle; inf. app. of male with lateral edges widely divergent, their two rami longer than the median length of the appendage; size larger (42-65 mm.) 5 5. Hind femora not extending beyond the middle of abd. seg. 2 and bearing only the usual numerous short ventral spines Gomphus Hind femora reaching the base of abd. seg. 3 and bearing 4 to 7 long ventral spines in addition to the usual short ones Dromogomphus NYMPHS 1. Abdomen subcircular, very flat; head behind the eyes bearing two large and two smaller spines; fore and middle legs without tibial burrowing hooks Hagenius Abdomen much longer than broad, less flattened; head behind the eyes without spines; fore and middle legs with tibial burrowing hooks (sometimes vestigial) 2 2. Palpal lobes of labium with apices rounded, without an end-hook 3 Palpal lobes of labium terminating in a recurved end-hook 6 3. With a mid-dorsal series of hooks or knobs; wing-cases divergent Ophiogomphus Without dorsal hooks or knobs; wing-cases with costal margins parallel 4 4. With small lateral spines on abd. segs. 7 to 9; third seg. of antennae about half as wide as long, widest in distal half; western Octogomphus 5. With very small lateral spines on abd. segs. 8 and 9 only; third seg. of antennae about three-fourths as wide as long, widest in proximal half; eastern Lanthus 6. Seg. 9 without a sharp mid-dorsal ridge ending in a straight spine, although a minute terminal spine may be present; vestigial dorsal spines sometimes present on some of the other segments Gomphus Seg. 9 with a sharp mid-dorsal ridge ending in a straight spine; small dorsal spines present on all abdominal segments except one and ten Dromogomphus

146

THE ODONATA OF CANADA AND ALASKA

SUBFAMILY HAGENUJSTAE Genus Hagenius Selys BuU. Acad. Belg., 21: 82, 1854. Type species H. brevistylus Selys. This is a monotypic genus, whose nearest relative is Sieboldius Selys of the eastern palearctic and oriental regions. Apart from its great size Hagenius differs from all other Canadian Gomphidae in the triangles of both pairs of wings, which are crossed, and the distal sides of which are broken near the distal angle, and in the larger number of antenodal and postnodal cross-veins, the longer and relatively narrower pterostigmata, the absence of any trace of a tibial keel on the fore leg§ of the male, and the form of the inferior anal appendage of the male, which is quadrate and not distinctly bilobed, the apical margin being merely slightly concave. The nymph is peculiar, not only in the great width and flatness of the abdomen, tie prominent dorsal hooks, and other characters noted in the key, but also in the form of the third antennal segment, which is flat and discoid, and in the straightness and comparative slenderness of the front and middle legs. The straight legs without tibial burrowing hooks testify to the fact that these nymphs are not burrowers like other gomphids but sprawlers amid the trash along the edge of the streams they inhabit. They are particularly likely to be found lurking under waterlogged flakes of bark. Hagenius brevistylus Selys. (Pi. 12: 1) Hagenius brevistylus Selys, Bull. Acad. Belg., 21: 82,1854. A very large black and yellow-green dragonfly with a relatively small head, stout thorax, long legs and slender abdomen, not greatly enlarged distally. Male. Face yellowish green with a narrow black line at base of labrum and on the median part of the fronto-clypeal suture; vertex and occiput black, rear of occiput yellow. Dorsum of pterothorax with the following parts yellow: the collar, anterior half of median carina and a narrow stripe on each mesepisternum, an antehumeral line and a spot in front of fore wings. Sides black with two broad yellow stripes and a narrow metepisternal line; metasternum largely yellow. Legs black. Interalar space and abdomen with an interrupted median yellow stripe, which breaks up on segs. 4 to 7 into narrow triangular spots; 8 with a wider rounded spot; sides of 1 to 3 and ventrolateral areas on 7 to 9 also yellow. Legs long, hind femora when extended reaching beyond the base of seg. 3, with numerous short stout spines, those of femora chiefly ventral and ventrolateral; tibiae with two ventrolateral rows of stout spines; continued on tarsi with smaller spines. Abdomen slender, cylindrical, widening distally, particularly on 7 to 10. Sup. apps. short, stout, with apices abruptly depressed, tridentate; inf. app. wider than long, with a shallow emargination, the posterolateral angles terminating in an upcurved tooth. Female similar except for the stouter abdomen, wider mid-dorsal yellow stripe and form of the terminal segments, 7-10 forming a small club, widest at 9. Vulvar lamina about one-third as long as the sternum of 9, twice as wide as long; the distal margin obtusangularly notched.

FAMILY GOMPHIDAE

147

Anx $ 14-16/15-18, $ 13-16/12-14; pnx $ 9 13-18; primary anx 1 and 6 or 7(8). Measurements. Total length $ 71-79, 9 74.0-84.5; abd. $ 51-54, 9 56-57; h. w. $ 47-50, 9 49-50; h. f. $ 9 14-15; pt. $ 4.5-5.0/5.1-5.3, 9 5.2-5.7/5.5-6.0. Nymph (pi. 54: 1). The nymph has been fully described by Garman (1927). It can easily be recognized from the figure. A few of its peculiar features, however, may be noted here. It has the broadest, flattest abdomen of all our Anisoptera. The frontal region of the head is flat and declivent, like a snow plow. The third segment of the antennae is subcircular and contiguous with its fellow, the pair lying together on the same sloping plane as the frons. The labial mask is as broad as long and the palpal lobes are also relatively broad and rounded at their apices, there being no end-hook. The legs are long, especially the hind pair; the femora are all straight and the tibiae without burrowing hooks. Segs. 2 to 7 of abdomen bear dorsal hooks or carinae, the hooks being large on the more anterior segments but reduced caudad until they are mere ridges on 8 to 10. There are sharp lateral angles on 2 to 9. The colour is nearly uniform dark reddish brown. Length 25-40; abd. 22-23; h. w. 8.5-9.0; h. f. 11.5-12.0.

Habitat and range. Forest streams with a more or less perceptible current, or rocky channels between Precambrian lakes. N.S. to e. Man., s. to n. Fla., Ky., and Tex. Also recorded from Colombia and, apparently erroneously, from B.C. Distribution in Canada. N.S.—Annapolis, Hants and Halifax counties. N.B.—Queens (Grand Lake) and Gloucester counties. Que.—Otter Lake, Hull, Wakefield, Bernard Lake; Mt. Tremblant Park, Laurentian Highlands. Ont.—York, Northumberland, Simcoe, Victoria, Peterborough, Leeds, Carleton and Renfrew comities; Muskoka, Parry Sound, Nipissing (including Algonquin Park), Thunder Bay and Kenora (Lake of the Woods) districts; Man.-Berens River (52°25/N). Field notes. This huge gomphid is fairly common in the eastern provinces, particularly in the Precambrian regions, where the network of lakes, channels and streams furnish ideal conditions for the development of the nymphs. While engaged for several summers in biological investigations at Go Home Bay, Georgian Bay, we had an opportunity of observing Hagenius throughout its entire flight period. In this part of Ontario emergence usually begins about the third week in June and is over early in July. For a few days the tenerals stray over the rocks or along the borders of woods, flying rather slowly at the height of a few feet and settling frequently on bushes or on the rocks. At Go Home Bay they were often seen basking in the sun in sheltered openings in the thickets along the shores of the river. Later, when fully mature the males were often seen flying swiftly over the water, close to the shore, with the end of the abdomen decurved. The flight period is moderately long, lasting until about the third week in August. Hagenius is remarkable for feeding largely upon other dragonflies, such as Gomphus (G. lividus and exilis), Tetragoneuria and Neurocordulia, but we have seen it in Algonquin Park catch a moth during flight. We have not noted the ovipositing habits carefully, but Needham and West-

PLATE 25 Aeshnidae—anterior lamina and anterior hamules (males), ventral view: (1) Gomph

aeschna furcillata; (2) Eoyeria vinosa; (3) Nasiaeschna pentacantha; (4) Epiaeschna

héros; (5) Basiaeschna Janata; (6) Anaxjunius.

FAMILY GOMPHJDAE

149

fall (1955) give the following statement: "Females oviposit while flying, in a zig-zag course, circling over a comparatively small area of open water, rising and descending and lightly striking surface with tip of abdomen to wash off a little cluster of eggs at each descent." Full-grown nymphs were found at Go Home Bay during the first half of summer among roots and debris along the edge of the river or lake shore. They are found in the bay and river but are absent from the smaller inland lakes, which are all more or less marshy or boggy. They do not, however, frequent the barest or most exposed parts of the shore but show a preference for the more sheltered spots, where the bottom is more or less sandy. The younger nymphs are occasionally dredged from depths of six or eight feet. Four sizes of nymphs were found, including full-grown ones. It would thus appear that the nymphal life extends over a period of four years or more. SUBFAMILY GOMPHINAE Genus Ophiogomphus Selys Bull. Acad. Belg., 21: 39,1854. Type species Aeschna serpentina Charpentier. Diastatomma Kirby, Syn. Cat., p. 61,1890. This is a genus of medium-sized gomphids found chiefly in clear mountain streams. They are green or yellow-green, marked with brown, only the legs being black, partly or wholly. The anal loop of the hind wings is short and rounded and usually composed of three cells, though varying from two to four. The abdomen of the male, and in lesser degree that of the female, are moderately widened towards the posterior end, segments 7 to 9 being included in the expansion. The inferior anal appendage of the male is often nearly as long as the superior appendages and is rounded or expanded distaUy, with a comparatively shallow median cleft, which may be slit-like, sometimes with the two lobes meeting, or it may take the form of a small open notch, in which case the lateral margins may be angulate. The occiput of the female is sometimes armed with a pair, or two pairs, of spines or horn-like processes, and sometimes an irregularly conical process, the postocular horn, arises from the rear of the head, behind the occiput and close to the edge of the compound eye. In general the species of Ophiogomphus are somewhat uniform in size, form and colour-pattern, both in the adult and larval state. The nymphs (pi. 55: 1) are, in fact, extremely uniform and difficult to sepa-

150

THE ODONATA OF CANADA AND ALASKA

rate, although the generic characters are well marked. They are all rather short, somewhat depressed nymphs with divergent wing-cases and a somewhat abruptly pointed abdomen, which bears a series of stout dorsal hooks or knobs. The third segment of the antennae is usually narrowly spatulate; the prementum of the labium short and wide with the sides distally subparallel, and the ligula evenly arcuate, bearing a number of "minute quadrate denticles at the base of the scale-like hairs" (Needham and Heywood, 1929). The distal ends of the palpal lobes are rounded and the mesal edges are finely denticulate. The distal end of the male projection appears as a pair of ante-apical tubercles. The genus is holarctic, but by far the greater number of species is North American. Needham and Westfall (1955) describe sixteen species, of which we recognize fourteen as valid, and of these eight are found in Canada, one of them having two subspecies. O. colubrinus and O. severus montanus are distributed much farther northward than any other species of Gomphidae in North America. The species of Ophtogomphus are typical of trout streams, brooks and small rivers, particularly where die original conditions have been little altered. They are found over most of Canada, where dragonflies occur at all, but are rare in cleared and cultivated regions, the nymphs being sensitive to alterations in the rate of flow of the stream and the silting that usually results from such changes. The nymphs are sometimes very abundant in brooks whose ecological conditions have been unaltered by man's interference. As the nymphs lie in the stream bed, barely concealed by the sand, it is not surprising that they are easily disturbed by alterations of flow. KEY TO THE SPECIES OF OPHIOGOMPHUS Moles 1. Face transversely striped with black 2 Face uniformly pale 3 2. Sup. apps., in dorsal view, somewhat bowed, separated by a U-shaped space, apices blunt; inf, app. nearly as long as sup. apps. colubrinus Sup. apps., in dorsal view, triangular with straight edges, separated by a V-shaped space, apices acute; inf. app. shorter than sup. apps. anomalus 3. Tibiae black 4 Tibiae with extensor surfaces yellow 6 4. Inf. app. much shorter than sup. apps., not projecting laterally beyond the sup. apps. aspersus Inf. app. as long as sup. apps. or a little shorter, its angular lateral edges projecting beyond sides of sup. apps. 5 5. Inf. app. with a deep but narrow cleft, its lateral edges with a toothlike prominence; abd. segs. 8 and 9 black without a median yellow spot mainensis

FAMILY GOMPHTOAE

151

Inf. app. wtih a relatively shallow U-shaped cleft; its lateral edges merely angulate; each abd. seg. with a median yellow spot carolus 6. Vertex with postocellar ridge strongly sinuate; apices of sup. apps. acute severus Vertex with postocellar ridge not sinuate; apices of sup. apps. rounded 7 7. Stripe 1 absent, stripe 2 faint and ill defined; inf. app. distokteral angles and a U-shaped median cleft rupinsulensis Stripes 1 and 2 both dark and clearly defined, 2 sometimes united with 3 into a single broad stripe; inf. app. without distolateral angles, median cleft narrow and slit-like at apex ocddentis Females 1. Face striped transversely with black 2 Face uniformly pale 3 2. Occiput without spines but with a definite transverse fringe of hairs; postoccipital horns stout; thorax without a dark interpleural stripe colubrinus Occiput with a median pair of black spines but without a definite fringe of hair; postoccipital horns very small; thorax with a dark interpleural stripe anomalus 3. Postoccipital horns absent or small and inconspicuous 4 Postoccipital horns stout and conspicuous 7 4. A pair of high median contiguous occipital spines present; abd. segs. 8 and 9 black without yellow spots mainensis Occipital spines, if present, small and well separated; abd. segs. 8 and 9 each with a yellow spot 5 5. Stripe 2 absent or represented by an elongate isolated spot, chiefly on the posterior half of the mesepisternum; postoccipital horns and occipital spines absent; extensor surface of tibiae yellow; western severus Stripe 2 narrow, somewhat sinuous and united in front with stripe 3; tibiae black; eastern 6 6. Small postoccipital horns present; occiput without a distinct fringe of hairs; median yellow spot of seg. 8 pointed behind, that of 9 rounded aspersus Postoccipital horns absent, occiput with a fringe of dark hairs; median yellow spot on seg. 8 blunt behind, that ot seg. 9 transverse carolus 7. Median thoracic stripes dark brown, distinct; dorsal occipital spines situated at lateral ends of occipital ridge, well marked; western ocddentis Median thoracic stripes absent or very faint; dorsal occipital spines small and slender, not at the extreme ends of the occipital ridge, sometimes absent; eastern rupinsulensis

PLATE 26

Aeshna—anterior lamina and anterior hamules (males), ventral view: ( 1 ) A. eremita; (2) A. interrupts; (3) A. verticalis; (4) A. canadensis; (5) A. clepsydra; (6) A. tuberculífera; (7) A. júncea; (8) A. subarctica.

FAMILY GOMPfflDAE

153

Nymphs 1. Lateral spines on abd. segs. 7-9 2 Lateral spines on abd segs $-9 .. occidentis 2. Seg. 4 of antennae minute, much narrower than seg. 3, from which it is sharply delimited; seg. 3 more or less narrowed before the apex 3 Seg. 4 of antennae as broad as apex of seg. 3, from which it is not sharply delimited; seg. 3 not narrowed distally anomalus 3. Seg. 3 of antennae spatulate, 2.5 to 3 times as long as broad; apex of epiproct of male extending not more than one-third of its length beyond the ante-apical tubercles, which project scarcely, if at all, laterad of the epiproct 4 Seg. 3 of antennae subelliptical, twice as long as broad; apex of epiproct of male extending not more than one-third of its length beyond the ante-apical tubercles, which project laterad of the sides of the epiproct mainensts 4. Length of cerci twice the median length of seg. 10, their basal width not less than half the length of their dorsal edge and less than twice their middle width; cuticular granules coarse and deeply pigmented 5 Length of cerci 2.5 the median length of seg. 10, their basal width less than half the length of their dorsal edge and more than twice their middle width; cuticular granules finer, often no darker than the surrounding area 6 5. Seg. 3 of antennae 2.5 times as long as wide; cerci two-thirds as long as epiproct; dorsal knob on seg. 2 stout carolus Seg. 3 of antennae 3 times as long as wide; cerci nearly threefourths as long as epiproct; dorsal knob on seg. 2 of moderate size rupinsulensis 6. Cerci four-fifths as long as epiproct; dorsal knob on abd. seg. 2 more or less recurved; greatest width of abdomen about equal to combined lengths of segs. 7-10 and anal pyramid severus Cerci three-fourths as long as epiproct; dorsal knob on abd. seg. 2 erect, not or scarcely recurved; greatest width of abdomen a little less than the combined lengths of segs. 7-10 and anal pyramid 7 7. Dorsal hooks on segs. 8 and 9 apically acutangulate or rectangulate in dorsal view; lat. spines on segs. 8 and 9 equal; sides of prementum of labium distally barely divergent or parallel colubrinus

154

THE ODONATA OF CANADA AND ALASKA

Dorsal hooks on segs. 8 and 9 apically obtusangulate in dorsal view; lateral spines of seg. 9 smaller than those of 8; sides of prementum of labium distally slightly convergent asperus Ophiogomphus severus Hagen. (PL 10: 3; pi. 35: 1; pi. 36: 1, 2; pi. 37: 1; pi. 38:1) Ophiogomphus severus Hagen, Geol. Surv. Terr. Col., p. 591, 1874. Herpetogomphus severus Selys, Bull. Acad. Belg., 46: 480,1878. This species is recognized by a combination of the following characters: (a) a sinuous postoceflar ridge, (fo) the absence or peculiar form of stripe 2, which is reduced to an oblique elongate spot on die posterior half of the mesepisternum, (c) the form of the anal appendages and the hamules of the male, and (d) the absence in the female of either occipital spines or postoccipital horns. Two subspecies have been recognized, both of them known from our territory. They appear to differ only in the intensity of the dark markings, and may be separated as follows: Stripe 1 confined to the median carina and along the ante-alar ridge to the posterior end of the mesopleural suture; stripe 2 absent or very small, stripes 3, 4 and 5 absent; abd. seg. 1 without dark dorsal spots O. severus severus Stripe 1 forming with its fellow a broad mid-dorsal band, twice as broad in front as behind; stripe 2 an oblique oval spot occupying more than half of the length of the mesepisternum; stripe 5 distinct and running the entire length of the metapleural suture; abd. seg. 1 with dark spots O. severus montanus Ophiogomphus severus severus Hagen. Ophiogomphus severus Hagen, Kennedy, Proc. U.S. Nat. Mus., 49: 341, 1915. Male. Entire face light yellow, vertex black in front, pale behind the ocelli; occiput and rear of head yellowish. Thorax pale green becoming yellowish olive in old specimens'* (Kennedy, 1917); dark markings greatly reduced or absent. Legs largely pale, femora with more or less dark brown cBstally on the dorsal surfaces of the femora and on the flexor surfaces of the tibiae and most of the tarsi. Abdomen with the yellow dorsal spots very extensive and, on most of the segments, uniting in front with the yellow ventrolateral areas, the dark areas brown; segs. 7-10 mostly yellow; anal apps. yellow. Anterior hamules deeply bifid, posterior hamules with spatulate tips. Sup. apps. in dorsal view somewhat convergent, with acute apices, outer edges somewhat convex, inner edges concave at basal half, with a mesal tooth at base; in profile slightly arched; ventral surface with many small denticles; inf. app. a little shorter than sup. apps., concave, with lateral edges convex towards base and concealed by sup. apps.; median cleft a narrow slit extending to the paraprocts; apex pointed, the two lobes contiguous.

FAMILY GOMPHIDAE

155

Female similarly marked. Vulvar lamina slightly more than half as long as seg. 9, two-thirds to three-fourths as wide at base as long, the outer edges somewhat convex, except at apex, where the apices of the two lobes are divergent; median cleft extending nearly three-fourths of the length, the two lobes contiguous before the divergent apices. Anx $ 11-12/8-9, 9 12-13/&-9; pnx $ 8-10/7-10, $ 8-11/8-10. Measurements. Total length $ 48-50, $ 49.0-51.5; abd. $ 34-35, $ 37.0-37.5; h. w. $ 30.5-31.0, $ 31.0-32.5; h. f. $ $ 6.5-7.0. Nymph. Robust in appearance, owing to the relatively broad abdomen; pale yellowish brown (in alcohol) or grayish brown (exuvia), without definite markings; hairy; cuticular granules small, not deeply pigmented. Labium, when folded, attaining tne hind edge of the prosternum; sicfes or prementum diverging distad of the contracted proximal part, ligula bearing 26-35 piliform setae, its arch faintly subangulate. Abdomen in exuviae somewhat depressed and broader than in other species (except occidentis), its greatest width equal to about the length of the last four segments together with the anal pyramid. Dorsal hooks on segs. 2 and 3 somewhat high, tapering and recurved; on the remaining segments gradually lower and more horizontal, on 8 and 9 becoming almost straight in profile with acute projecting apices, viewed from above acute or rectangulate; lateral spines on 7-9, about equal, slightly divergent on 7; lateral margins heavily fringed with long hairs. Anal pyramid very nearly as long as 9-10; epiproct somewhat acuminate, its oasal width equal to about four-sevenths of its length; cerci about four-fifths as long as epiproct, their basal width less than half the length of their dorsal margin, tapering to slender-pointed apices. Length 25.5-27.5; abd. 17-19; w. abd 7.5-8.0; h. w. 6; h. f. 5. (Based on Walker, 1933, p. 227.)

Habitat and range. Streams and sometimes lakes with gravelly beds and beaches. Calif, to Col. and Neb., n. to Wash., Idaho, Alta. and Sask. Distribution in Canada. Alta.—Claresholm, Red Deer, Iddesleigh, Ft. McMurray. Sask.—Prince Albert. Field notes. Whitehouse (1918) states that, in the vicinity of Red Deer, Alta., this insect "frequents sandy roads near the river and rests on the soil frequently." His dates of capture during two years of collecting were July 13 to September 10, the majority having been taken during the second half of July and the first week of August. Tenerals were taken on July 13 and August 4. Kennedy (1915) observed O. severus on Satus Creek, Yakima Co., Wash., from June 15 to August 24. During this period emergence was observed from the second week of June until the first week of July, occurring from nine o'clock in the morning until four in the afternoon. The nymphs emerged chiefly from the mud-bottomed pools of the stream, seldom crawling more than six inches from the water. Oviposition, on the other hand, was performed almost altogether from stones in the rapids, "A female will fly out from a seat on a stone, make one tap in the water with her abdomen and then return to rest for a moment when she repeats the single tap" (Kennedy, 1917). "In copulation the male sought the female while she rested on a stone. Copulation occurred immediately after the male grasped the female, and after a short flight to a nearby bank the couple would rest in copulation for many minutes" (Kennedy, 1915).

PLATE 27

Aeshna—anterior lamina and anterior hamules (males): (1) A. septentrionalis; (2) A. sttchensts; (3) A. pálmala; (4) A. umbrosa; (5) A. constricta; (6) A. calif arnica; (7) A. multicolor. Tanypteryx hageni, anal appendages: (8) dorsal; (9) lateral. Anax junius: (10) palpal lobes of nymphal labium.

FAMILY GOMPHTOAE

157

Ophiogomphus severus montanus (Selys). Herpetogomphus montanus Selys, Bull. Acad. Belg., 46: 430,1878. Ophiogomphus montanus Muttkowski, Cat. Odon. N. Amer., p. 84, 1910. Ophiogomphus severus montanus Kennedy, Proc. U.S. Nat. Mus., 52: 533, 1917. This subspecies differs from O. s. sevens in the greater extent and depth of the dark markings. The darkest thoracic stripe, formed of the two first stripes, the long oval spots representing stripe 2, which occupies the posterior three-fifths to three-fourths of the dorsal length. Stripe 3, running the whole length of the mesopleural suture, is narrow in front but widens behind. Stripe 4 extends a little above the metaspiracle and continues forward around the lower edge of the mesepimeron; stripe 5, a narrow band of even width, covers the metapleural suture ana is continued around the metinfra-episternum. The dorsal femoral stripes are prolonged proximad nearly or quite to their bases. Abdomen black above with median series of sagittate yellow spots smaller than in O. s. severus and more completely isolated from the yellow ventrolateral areas. Anx 3 10-13/8-9, $ 12-14/8-10; pnx $ 9-11/9-11, $ 9-11/9-12. Measurements. Total length $ 50-52, $ 46-53; abd. 3 35-36, $ 31-38; h. w. $ 34.5-35.0, $ 31-32; h. f. 7. Nymph apparently not certainly known but probably identical with O. s. severus.

Habitat and range. Not differentiated from severus, except that in Canada montanus has been found only in the Cordillera, whereas severus inhabits the Plains. Utah and Nev. to Wash., Mont, and eastern B.C., n. to Liard Hot Springs. Distribution in Canada. B.C.—Princeton, Summerland, Aspen Grove, Nelson, Crawford Bay, Kootenay Lake, Salmon Arm, Mabel Lake, Adams Lake, Canim Lake, Chilcotin Lake, Liard Hot Springs. AZta.—Jasper Park. Field notes. O. severus montanus appears everywhere to be a mountain form. Kennedy (1917) suggested that its darker coloration might be due to higher altitude, since montanus is found in Yellowstone Park at a higher altitude than the Columbia River and Colorado, where severus occurs, although it is geographically intermediate. Whitehouse (1941), however, notes that "at Red Deer, Alberta, the habitat of severus, the altitude is some 2700 feet," whereas the altitude of Crawford Bay, near Nelson, B.C., where montanus occurs is only 1,700 feet. Some other factor than altitude must, therefore, govern the distribution of these two subspecies. In Canada, from

158

THE ODONATA OF CANADA AND ALASKA

the little we know of their distribution, montanus is apparently restricted to the Cordillera, whereas severus is known only from the Plains. Whitehouse states that montanus flies from the second week in July to the fourth week in August. Both montanus and severus "delight in disporting themselves along sunny roads, and to rest upon the warm surface." We found montanus "flying along a railway track on the mountain slope just above the city of Nelson. They showed a marked tendency to alight upon a rail or the edge of a railway tie and this habit, together with their extreme wariness, made them very difBcult to stalk." As montanus was taken at other stations along the shore of Kootenay Lake, we consider the lake itself to be probably the habitat of the nymph. Ophiogomphus colubrinus Selys. (Pi. 35: 2; pi. 36: 3, 4; pi. 37: 2; pi. 38: 2) Ophiogomphus colubrinus Selys, Bull. Acad. Belg., 21: 40,1954. A sturdy species; green, strongly marked with dark brown and black, the most northerly in distribution of all American Gomphidae. Male. Labium greenish, darkened on free edge of middle lobe; face light green; labrum with free margin and a basal transverse line black; free margins of postclypeus on each side black, and a black line on the fronto-clypeal suture; vertex black, occiput greenish with a transverse fringe of dark hairs. Pronotum brown with front margin and paired tubercles on median lobe pale. Pterothorax green, striped with dark brown; stripe 1 slightly more than half as wide as the adjacent green area, 2 and 3 broad, united in front and often behind, together as wide as dorsal green area, the narrow intervening green stripe curved up at the posterior end; stripe 4 extending a little above the metaspiracle; stripe 5 of even width, along the entire length of the metepimeral suture and bordering the mesinfra-episternum. Anterior surfaces of femora green, middle and hind pair black at apices and narrowly along the dorsal surfaces; tibiae and tarsi black. Abdomen dark brown and black with the usual dorsal series of yellow spots, which on segs. 3-7 are triangular with wide bases and contracted about the middle; spot on 8 almost parallel-sided, with acute apex; on 9 rounded and almost as broad as long. Segs. 7-9 with wide pale lateral areas; lateral spots on the other segs. less distinct, not clearcut. Anal apps. longer than 10; sup. apps. bowed with bluntly rounded apices, gently arched in profile; inf. app. almost as long as sup. apps., their lateral margins concealea in dorsal view; in profile straight with a sharply upturned apex, the dorsolateral outline obtusangulate before the middle; median cleft more than halfway to base, straight and narrow. Male genitalia, see pi. 38: 2. Female similar to male in size and colour-pattern, but with wings slightly longer; the stouter abdomen marked in a similar manner. Postocellar ridge M-shaped; occiput with a transverse fringe of dark hair, without spines; postocular horn moderately stout. Vulvar lamina about three-fifths as long as the sternum of seg. 9, triangular with base nearly as wide as long, slightly convex proximally, apex acute, median cleft narrow, extending halfway to base. Anx $ 13-14/9-11, 9- 12-16/9-11, pnx $ 10-11/9-12, $ 10-12/10-13; the primary antenodals are normally the first and fifth. Measurements. Total length $ 45.(M8.5, $ 45-49; abd. $ 29-34, $ 32-35; h. w. $ 26-28, $ 27-31; h. f. $ $ 6.5-7.0; pt. $ 3.0-3.4, $ 3.8-4.0.

FAMILY GOMPfflDAE

159

Nymph. Of medium to large size, nearly uniform brown or obscurely blotched, not very hairy; cuticular granules fine, somewhat darker than the ground colour. Third segment of antennae spatulate, slightly more than three times as long as broad. Folded labium attaining hind margin of prosternum; prementum contracted in the basal third, beyond which the sides are barely divergent, greatest width at distal end; ligula with 23-27 piliform setae. Dorsal hooks well developed on all abd. segs. (2-9), somewhat abruptly elevated, decreasing but little in height caudad but increasing in length, the apices changing from a perpendicular to a horizontal position, being erect and slender on seg. 2, arcuate on 8 and 9 with projecting apices, which are angiUate in dorsal view, that of 9 usually acute; lateral spines on 7-9 nearly equal, those on 7 parallel or faintly divergent, the others slightly convergent. Anal pyramid as long as 9 + 10 or barely longer; epiproct somewhat acuminate, its length about twice its basal width; ante-apical tubercles of male about two-thirds or five-eighths of the length from base. Cerci about three-fourths as long as epiproct, shaped as in severus. Length 26.0-29.5; abd. 16-20; w. abd. 6.5-7.5; h. f. 4.7-5.0; h. w. 5.5-6.0.

Habitat and range. Clear rapid streams with gravelly or sandy beds. Nfld. to Hudson Bay and Mackenzie, s. to Me., lower St. Lawrence and Gatineau Valley, Que., Renfrew Co., Ont., n. Mich,, Wis., n. Man., Sask., Alta. and B.C., near Ft. George. Distribution in Canada. N/W.-Trinity Bay. £t*0.-Gatineau Valley; Nominingue; Port Neuf; Godbout; La Ferme, Abitibi Co.; Grand Remous; Hudson Bay. Ont—Renfrew Co.; Manitoulin, Nipissing (incl. Algonquin Park); Thunder Bay, Cochrane and Kenora districts; n. to Ft. Albany and Ft. Severn. Man.—Gillam; mile 332, Hudson Bay Ry. Sask.—Wapus River, Reindeer Lake; Stanley, Churchill River. Alta.—Ft. McMurray; Athabasca delta. B.C.-Vicinity of Prince George. N.W.T.—Mackenzie; Ft. Smith. The known northern boundary is as follows: Godbout, Que. (49°20'N), Ft. Severn, Ont. (55°50/N), Athabasca delta (58°2