A. V. Hartynov.
The Interpretation of the Wing Venation and Tracheation of the Odonata and Agnatha.
Psyche 37:245-280, 1930.

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19301 Wing Venation of the Odonata and Agnatha 245 THE INTERPRETATION OF THE WING VENATION
AND TRACHEATION OF THE ODONATA
AND AGNATHA.l
Custodian,
Zoological Museum of the Russian Academy of Science, Leningrad
Translated, with an introductory note, by F. M. Carpenter.* INTRODUCTION
In 1922 Dr. A. V. Martynov read a paper before the Entomological Society of Russia on the interpretation of the veins and trachese in the wings of the Odonata and Agnatha (Plectoptera) . His manuscript was turned over for publication in 1923 and after some delay was finally published in Russian the following year (Rev. Russe Ent., 18 (4) :145-174). In connection with my investigations on fossil insects, I found it necessary to consult his paper, and from the very short French summary at the end of the article, I felt sure that the text contained important data and discussions which should not be overlooked. I therefore employed Miss Olga Jahr, of the Slavic Depart- ment of the Harvard Library, to assist me with the trans- lation of the Russian. Naturally enough, Miss Jahr was unfamiliar with the biological terms, but by working to- gether we obtained a complete English translation without much difficulty. As the translation progressed it became more and more evident that the text was fully as important IThis paper is
an enlargement of the report which was read at the Russian Entomological Society, November, 1922; the manuscript was handed to the press in May, 1923.
* National Research Fellow, Harvard University.



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246 Psyche [ September
as I anticipated, and when the task was finished, I decided to publish the entire translation of this paper in order that it might be available to other investigators of insect phylogeny. Although there are several points on which I cannot agree with Dr. Martynov, I nevertheless consider this paper one of the outstanding contributions to insect phylogeny published during the past decade. Dr. Martynov kindly assisted me in locating several mis- prints which occurred in the original text, and which had naturally caused me much confusion. The twelve figures accompanying the original article are essential for a com- plete understanding of the problems under discussion. Unfortunately, these figures were very poorly printed, and could not be copied for reproduction here without consid- erable retouching. Since there is always a possibility of distorting a figure during this process I decided that it would be better not to reprint the figures at all, but to refer the reader to the original ones. While this procedure, involving the use of two publications, may be somewhat inconvenient, I believe it introduces the lesser of two "evils." -.F. M. CARPENTER.
Comstock and Needham published (4) their first data on the interpretation of venation of the Odonata and Ag- natha in a series of articles on the wings of insects, which appeared in 1898 and 1899; and in 1903 Needham developed (10) these ideas with more details into a large work on the venation of Odonata. The interpretation of Odonate venation which was proposed in both works mentioned above was later accepted by the majority of Odonatolo- gists and by Handlirsch (6). According to this inter- pretation the nervuration of the Odonata proved to be so peculiar that it could hardly be compared even with that of the Agnatha-the very closest group.
The most characteristic features of this venational sys- tem are the following: 1, the crossing of the radial sector by the bases of Mi and Ms, and its extension into the region between Ms and Ms. 2, the large size of the media, with 4 branches; M4 always leading from the base of M.



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19301 Wing Venation of the Odomta and Agnatha 247 3, the curve of the cubitus (chiefly in the Anisoptera) and beyond this curve, the formation of the two branches, Cui , and Cus ; formation of a triangle (or quadrilateral. 4, small size of the anal vein and its fusion with the cubitus. It is necessary to add that according to the authors' understanding the continuation of RS to Mi+a is clearly a secondary vein ("bridge") and appears to be the basal part of the analogous vein indicated by Tillyard (14). The venation of the Agnatha, as usually interpreted (Eaton. Cornstock 1899, Handlirsch, Ulmer and others), is entirely different from that of the Odonata, and much more similar to that found in the more primitive Palm- dictyoptera (Dictyoneuridas) . The media is simple and forks only in the distal part; RS is large and forms 4-5 branches; Cu is divided at the base, and the down curve is formed only by the lower branch; the anal veins are well developed. These differences in the interpretation of the wings of the Odonata and Agnatha are so great that the dragon-flies would on this basis be moved far off from the may-flies; but this contradicts the sum of all data in morphology and the development of these insects. If vena- tion means anything in the explanation of phylogenetic relations of the different groups~as is unquestionably so, and the venation of the dragon-flies has been studied par- ticularly carefully from this point of view-then either the evidence of morphology and history of development, which indicate a close relationship of the Odonata and Agnatha, are wrong; ox the interpretation of the wing venation of Odonata or perhaps the Agnatha is incorrect. As the close relation between the Odonata and Agnatha is not disputed, the author began to doubt the accuracy of the usual interpretation of venation of the may-flies and partly of the dragon-flies.
It is well-known that Cornstock and Needham based their interpretation of the wing venation in different groups on the study of the tracheation of the wings of nymphs and pupse. This tracheation, it is supposed, reflects the more primitive condition of venation. The trachea RS of the Odo- nata (Anisoptera) turns off from R and, after crossing the bases of trachea" MI and Ma. enters the region between



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248 Psyche l September
Ma and Ms; tracheae which go into these latter veins and , into M4 of the authors, join at the base into one common trunk, which enters the wing independently. Hence the conclusion that this trunk is M, that RS crosses Mi and Ms, that the bridge is a secondary formation, that the cubitus is two-branched, etc. Among the may-flies Corn- stock discovered at first a type of tracheation very dif- ferent from that of the dragon-flies, and nearer to the normal. From this tracheation Comstoek was led to an interpretation essentially similar (if not in names) to the one of Eaton (5) and other authors. Ann Morgan (8) undertook a careful investigation of the tracheation of dif- ferent species of may-fly nymphs and discovered that the tracheal stem which sends small tracheae into the branches of Cornstock's RS usually arises independently from the common tracheal wing stem. Consequently, she concluded that the system of veins which include these traeheee do not represent RS, but M, as in the Odonata. Usually in the may-flies the trachea ES does not arise from the trachea R, as it does in dragon-flies; but in one species of Heptagenia, and even then only in part of this specimen, Morgan succeeded in finding a weak trachea which led off from R, crossed M and entered into the region between Mi and Ma. Following' the ontogenetic method of Corn- stock, Morgan concluded that the may-flies also originally had the radial sector cross the media.
Cornstock, in his later work on the wings of insects (31, which represents an enlarged and somewhat changed edi- tion of the joint work of Comstock and Needham (41, agreed with the results of Morgan and accepted, therefore, her interpretation of the wing venation of may-flies. By this interpretation the venation of the may-flies was brought (to a certain degree) up to the scheme2 of the venation of the dragon-flies; but by the same interpretation the Ephemerid venation appeared to be extremely remote from that of the Palseodictyoptera and even the Carboniferous TriplosoMdss Hand!. Although the latter are placed in Only to a certain degree, because Ra of the may-flies in Morgan's paper Is sot this vein in the dragon-flies. In the latter Ra (of author's) corresponds to our Rs,, and & (Morgan and Cornstock) of the may- flies corresponds to our R83.




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19301 Wing Venation of the Odonata and Agnatha 249 a special group by Handlirsch, Protephemeroidea, which combines the characteristic venational features of the more primitive Dictyoneuridee and the specialized features of may-flies, nevertheless they still are Ephemerids, which preserved only the anterior branch of M of the Dictyo- neurida? (MA). As to the dragon-flies, Needham's inter- pretation aroused doubts only in its application to the Zygoptera. The trachea which supplies RS in the latter arises from M2, not from R, and in general no tracheae which lead from R enter into the I-egion of M. But Com- stock and Needham think that here also, the vein RS enters into the region between Mo and M3, and that trachea RS used to arise from R and cross the media, but later "de- tached" itself from R and "attached" itself to Ms. Since it is difficult to support the last supposition by definite proofs-there are none-Tillyard (15) and Rice (12) naturally expressed3 doubts about the Zygoptera having RS. Munz, however, pointed out (9) that the conformity of the vain veins of Zygoptera and Anisoptera is so evident that it is impossible to interpret the venation of Zygoptera different from that of the Anisoptera, and accepted the old scheme of Needham.
As I approached the study of the venation of dragon- flies and may-flies I thought that if the dragon-flies and Ephemerids were Palseoptera,* i. e., insects which never fold their wing's on the back (roof-like) at rest, then not only the may-flies but also the dragon-flies should preserve the features of venation of the related Palaeodictyoptera. If the venation of dragon-flies, according to the interpreta- tion of Cornstock and ~eedham, proves to be so unusual that it puts them in an entirely isolated group among the insects, the cause of such a situation evidently lies in the wrong interpretation of the venation by these authors and the uncertainties of the ontogenetic method. It is neces- sary to note that at one time Redtenbach (11) offered an entirely different interpretation of the venation of dragon- flies; attaching great importance to the alternation of con- .
Citing after Munz (9).
4Concerning the division of the Pterygota into Paleoptera and Neoptera, see my paper (7).




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250 Psyche [ September
cavities and convexities of the wing, the author compared their dispositions in dragon-flies and may-flies, and came to the conclusion that they are very similar in venation as well as in the alternation of concavities and convexities. Unfortunately this author, following the erroneous concep- tion of Adolf (1) concerning the different origins of "convex" and "concave" veins in the first stage of the "fan" type of wing and the disappearance in other insects of a series of "concave" veins, came to an incorrect homologization of the veins of the two groups mentioned with those of other insects. Thus the cubitus of Ephemerids (and dragon- flies) he indicates by the number viii, which in other insects corresponds to Ai; the median by number vii, which corresponds to the cubitus, etc. Denouncing the earlier views of Adolf, Comstock and Needham also did not attach any importance to the similarity in the wing venation be- tween the may-flies and dragon-flies, which was observed by Redtenbach.
It always seemed to me very risky to depend upon Com- stock's and Needham's ontogenetic method for the explana- tion of the homology and evolution of venation. When we study the tracheation of nymphs and pupae we study at the same time the ontogeny of tracheation, but not vena- tion at all, because veins are vessel-like forms in which the blood circulates and into which nerves and usually tracheae often enter; but there can exist veins without tracheae. On the other hand, the thinner tracheae which we observe in the nymphs and young imagines of dragon-flies and nymphs of may-flies go through the wing and outside of veins in great numbers and often do not connect the neighboring veins, but the ones lying far apart. As to the formation of veins, although it was previously supposed that they were formed originally by the tracheae, more re- cent investigation~ have shown, especially in rather primi- tive groups [see, for example, the work of Marshall (17) on the development of the wings of the Trichoptera], that in the wing adage the venation is formed before the tracheae pierce through. Comstock and Needham sup- posed that the tracheation in the wing of a pupa and nymph reflects the primitive state of venation. Therefore one would suppose that in the forms with a venation which resembles



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19301 Wing Venation of the Odonata and Agnatha 251 especially closely the scheme of the original venation, we should expect a particularly complete parallelism of the tracheation with the venation. But this is not so. In Hydropsyche, which is a small caddis-fly with extremely primitive venation, Comstock and Needham found a com- plete unconformity of the tracheation with the venation, which they interpret without regard for the direction of the trachea. These authors are obliged to do the same with the Hymenoptera and Diptera. Why should we rely so blindly upon the tracheation in case of dragon-flies and Ephemerids and
ignore the data of paleontology, which
proves the close relation of venation in contemporary repre- sentatives of dragon-flies and may-flies with that of the Palseodictyoptera (in the case of the Ephemerids, through the Carboniferous Triplosoba Handl.) ? Such a "concep- tion" is all the more unacceptable because the theory of Comstock and Needham encounters serious contradictions within the groups themselves. The crossing of the media which arises from R by means of the trachea RS takes place only in the Anisoptera; this does not appear in the Zygoptera, and the trachea of the corresponding vein arises from the branch M. We have no proofs that the latter condition developed from the former. As to the Aniso- zygoptera, in view of their very close relationship to the Agrionidse (through the Lestinse), one can suppose that in them the trachea RS of the authors arises from the media of the authors. A very diverse and changeable tracheation of nymphs of may-flies gives us still less right to conclude that they have such a crossing, that their com- plicated vein below R is M, etc.
My investigation of the relation of the venation to the tracheation has led me to the conclusion that the formation of venation occurred under the influence of causes of me- chanical character; the tracheation, adapting itself to the newly formed distribution of veins, often changed in a most original way; therefore, one can judge the venation by such an "indirect" representation of it only with ut- most care.
In view of these facts I decided that in investigating the venation of dragon-flies and may-flies, as well as of other groups, to turn first to the comparative study of the vena-



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252 Psyche [ September
tion itself, at the same time constantly keeping in mind as much as possible the function of the venation, and changes which should appear in the phylogeny of the wing by the work of the separate parts of the wing and the work of its veins. Only after such investigation is it possible to approach the study of the history of tracheation, which depends upon the venation and reflects its history. This I will discuss at the end of this paper. Let us first turn to the Palseodictyoptera. The "family" Dictyoneuridse has the most primitive venation (figs. 1 and 2) ; the wings here are homonomous, hardly broadened at the base; sometimes their ends are somewhat pulled out and as if curved backwards (Stenodictya, Microdictya, Stilbocrocis, Polioptenus, et al) . RS in the more primitive forms (Stenodictya, Microdictya) arises from R approxi- mately at the middle of the wing, or a little nearer to the base; but in the majority of other forms we encounter the process of its receding towards the base. Usually RS sends 3 or 4 branches posteriorly, not counting its con- tinuation; in some cases the second branch (counting from the base) does not reach the trunk RS, but adjoins to the first and sometimes (Microdictya vdanti, Stilbocrocis, Eumecoptera) forks dichotomously. The media is divided into two branches, which we shall call M. anterior (MA) and M. posterior MA in this family, as well as in the majority of other Palasodictyoptera remains simple ; MP branches in the Dictyoneuridse, often forming three branches (Stilbocrocis, Eumecoptera, Dictyoneurula, Acan- thodictyon, partly Polioptenus) , in which it greatly reminds us of M in the Ephemerids. Normally the cubitus also di- vides not far from the base into two branches of which the first (anterior), CuA, usually remains simple as in Polioptenus and Eumecoptera (figs. 1 and 2) ; the posterior branch, CUP*, usually gives rise to smaller branches. In the very primitive forms the anal veins form a com- paratively homogeneous series of 3-4 veins, which gradu- The development and configuration of the media have just the same characteristics as R.
MA corresponds to the radius proper (R) ; MP, to the radial sector. The same was originally true of the cubitus (Cu).
* Misprinted MP in original.




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19301 Wing Venation of the Odonata and Agnatha 253 ally grow smaller nearer to the base; but the more special- ized Al is better developed, and others lose their indepen- dence, uniting either with Ay or even together with Ai. There is no need to discuss the other families, because their wings were already specialized in different directions from those in which the dragon-flies and Ephemerids are specialized.
All recent Agnatha differ sharply from the Palseodicty- optera, in that their fore wings are greatly enlarged at the expense of the hind pair (fig. 4), which have become completely reduced in many species (in sub-group Bsetoidea Ulm.). If the hind wings are present, the fore wings are wide and approximate a triangle; then, where the hind wings tend to disappear, the fore wings take the shape in the first group (Ephemeroidea and Heptagenioidea) , which corresponds more to the shape of the fore and hind wings taken together.
If the hind wings of contemporary Ephemerids differ greatly from the fore wings, this was not the case in the past. In the Ephemerids of the Permian the hind wings differed very little or not at all from the fore pair, and their form resembled very much that of the wings of Dic- tyoneuridse (13). Likewise, the wings of the remarkable Carboniferous Ephemerid Triplosoba Brogn. were homo- nomous (fig. 3). Handlirsch placed (6) this form into a special order, Protephemeroidea, because it preserved in its venation the features of the Palseodictyoptera, particularly of the Dictyoneuridse. Just as in Eumecoptera (fig. 2) and in many other Dictyoneuridss, RS arises nearer to the base and sends posteriorly the usual four branches, of which (and this is very important) the second branch, i. e. RS4, originates near RSs, and RSs and RS2, together with RS1, form the distal group. Evidently RSs, already form- ing the "inserted sector," did not reach RSl. M, as in
the Dictyoneuridse, is divided near the base into the same two branches, MA and MP; MA also, as in the Dicty- oneuridse, remains simple, while MP is divided distally into three branches, the middle one and the two supplementary ones beside it being already changed into "inserted sectors" (Schaltsectoren).
The close similarity of this MP with
M in the real Ephemerids leads us to believe that M of



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254 Psyche [ September
the may-flies is really MP, and their MA is reduced and has completely vanished. Cu is divided into two simple branches, in which one can also see CuA and CUP of the Palseodictyoptera. Then come the anal veins; the long Ai with its branches, and another long one, As or As, with its branches. The character of the cross-veins !is the same as in Ephernerids. As already mentioned the fore and hind wings in the may-flies of the Permian were alike, their shapes quite resembling those of the Dictyoneurid wings; but in all that is known to us, MA was already missing. The branching of RS is also very much like that of Triplosoba and of the contemporary Ephemerids, while here also (Protecha Sell., Protereisma Sell.) RS4 arises near ESe, and the rest of the branches form the distal group. The branches RSi and RSy represent "inserted sectors" as in the recent Ephemerids.
According to the interpretation of Sellards and Hand- lirsch, Cu is divided into two branches at the very base; the anterior of these also divides into two side branchlets and a middle "inserted" one (in Protechma) ; and the pos- terior branch gives rise to two small branches directed posteriorly. The anal region is badly preserved. On ac- count of this poorly preserved anal region it is difficult to say how to regard the two branches of the cubitus, whether they correspond to CuA and CUP of the Palseo- dictyoptera or whether there is another interpretation pos- sible. Incidentally, the anterior branch with its branch- lets is very much like the cubitus of Siphluridse, Ecdyuridae or Leptophlebiidse.
The fore wings of the recent may-flies, because of the division of labor between the wings (all work of production of strokes and stroking the air being transferred to the '
fore wings), increased their dimensions and took the shape of elongate triangles, as in many Papilionidse; as to the hind wings, where they are developed best of all-in Ephemeroidea and Heptagenioidea-they are of an oval or round shape as in many Rhopalocera, and in other may- flies-in Bsetidae, Ephemerellidse, and Caenid-they are subject to greatest reduction. The fore wings, substituting in these groups for the disappearing hind ones, grow wider in the cubital and anal region and take a shape which



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19301 Wing Venation of the Odonata and Agnatha 255 corresponds to the form of the fore plus hind wings in other groups, or to one wing of the homonomous group (Dictyoneuridse, Carboniferous and Permian Ephemerids) . Therefore, I think that the primitiveness of Bsetoidea wings is only an apparent one and that in the past their fore wings were also probably of triangular shape. The differences in dimensions and in the shape of both pairs, in their turn also, were formed for a second time, replacing the original homonomous condition. The venation inherited from the ancestors was not effected by the change in the shape of the wings, and it remained very much like that of such may-flies of the Permian as Protereisma, Protechma, and also as Triplosoba. The homologizing of veins in these last forms with those in the Dictyoneuridse is therefore not difficult and is correctly interpreted by Handlirsch. RS in Triplosoba also turned off (from R) at the very base, but here the place of origin (how, is another question) is still nearer to the base.
But more often Rs is derived (sec-
ondarily) from the basal part of M.* The branching of