G. C. Crampton.
The Genitalia and Terminal Structures of the Male of the Archaic Mecopteron Notiothauma reedi, Compared with Related Holometabola from the Standpoint of Phylogeny.
Psyche 38:1-21, 1931.

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PSYCHE
VOL. XXXVIII MARCH, 1931 No. 1
THE GENITALIA AND TERMINAL STRUCTURES OF THE MALE OF THE ARCHAIC MECOPTERON,
NOTIOTHAUMA REEDI, COMPARED WITH
RELATED HOLOMETABOLA FROM THE
STANDPOINT OF PHYLOGENY
Massachusetts Agricultural College, Amherst, Mass. For the rare privilege of studying the hitherto unde- scribed male of the intensely interesting archaic Mecopteron Notiothauma reedi, McL. (which is in some respects a "living fossil"-the last remnant of a primitive relict fauna, representing as closely as any living form, the type an- cestral to the rest of the Mecoptera) I am deeply indebted to Professor Dr. C. E. Porter, who has done so much to advance the study of Entomology in Chile, and to Dr. E. P. Reed, the distinguished Chilean surgeon, who has been more than generous in supplying me with a wealth of ma- terial for morphological study. To both of these gentlemen I would express my profound gratitude for their aid in enabling me to carry out this investigation. The abdominal structures of the male of Notiothauma are the most remarkable and primitive to be found within the order Mecoptera, and could readily serve as the arche- types of these structures for the rest of the order. The primitive character of these structures is thus in harmony with the evidence of the archaic character of Notiothauma indicated by other features such as the wings, which have been discussed in Psyche, Vol. 37, p. 83, for 1930, where



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2 Psyche [March
the male here described was designated as the allotype of Notiothauma reedi, McL.
The greater portion of the abdomen of the male of Notiothauma is of a castaneous color, but segments eight and nine (see fig. I), and the gonopods labelled ex and st in fig. 1, are somewhat fulvous hued. The abdomen is rather broad and is somewhat flattened, and does not taper as the abdomen does in the Panorpidae (sensu stricto), being more like the abdomen in the closely related family Mero- pidse in this respect, although the genitalia are much more primitive than those of Merope (which are elongated and rather highly specialized), and the genitalia of Notiothauma might readily serve as the archetype of the genitalia of the Panorpidse. On the other hand, the abdominal structures of Notiothauma present some remarkable modifications, which, with the general archaic character of Notiothauma, make it the most interesting and striking representative of the Mecoptera. Starting with the structures of the third abdominal segment and taking up the structures of the following segments in turn, I shall briefly describe the striking features of the abdomen, and point out wherein the structures of Notiothauma may serve as the starting point for tracing the evolutionary developments occurring in the other Mecopterous families.
In the posterior region of the third abdominal tergite of the male of Notiothauma there occurs a median unpaired structure labelled n in figs. 1 and 5, which, for the sake of convenience, may be referred to as the notorganus or notal organ. A conical median tergal structure labelled po in figs. 1 and 5, borne on the following (i. e., the fourth) ter- gite, abuts against the notorgan n, on the third tergite. I have followed Felt, 1896 (Kept. N. Y. State Entomologist for 1894, p. 463) in regarding the notorgan n as an alluring organ which gives out an exudate licked up by the female prior to mating. The notorgan n (and the posterior struc- ture po) is not developed in other primitive Mecoptera such as Merope, Chorista and Panorpodes, (and it is likewise absent in the Bittacidse, Nannochoristidse and Boreidse), so that Notiothauma furnishes the only starting point for tracing the development of these structures in the Pan-



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19311 Structure of Notiothauma reedi 3
orpidse, in which the structures in question may become hugely developed. In Panorpa stigmalis (fig. 27) the notor- gan n has become elongated and extends posteriorly to the cone po, which is located further back in segment four, while in Neopanorpa cornuta (fig. 26) the orthogenetic tendency for the notorgan n to become further elongated becomes more pronounced, since in the latter insect (fig. 26) the notorgan n projects posteriorly over the fourth tergite and nearly reaches the middle of the fifth tergite. In such Panorpids as P. takenouchii (fig. 29) the ortho- genetic tendency for the notorgan n to become more and more elongated, reaches its culmination. Since Notiothauma furnishes the only starting point, among the lower Mecop- tera, for the development of such a notorgan (n of fig. 1 and 5) this very clearly indicates that Notiothauma is the most like the ancestor of the Panorpidse. On the fifth tergite of Notiothauma there occurs a re- markable median unpaired tergal process labelled mo in figs. 1 and 5. This process is apparently peculiar to Notio- thauma, although a shorter process, resembling it in some respects, is borne on the sixth (instead of the fifth) ter- gite of P. cornigera, shown in fig. 32.
This process of the
sixth tergite of P. cornigera, abuts against the dorsal por- tion of the seventh abdominal segment, when the end of the abdomen is turned forward on top of the abdomen, while in No@othauma, the tips of the genital styles st of figs. 1 and 5 apparently lie on each side of the median pro- cess mo when the tip of the abdomen is turned up over the top of the abdomen of the male insect.
The sixth abdominal tergite of Notiothauma bears a pair of lateral tergal processes labelled he in fig. 1, which are somewhat suggestive of the paired lateral tergal processes borne on the sixth tergite of Neopanorpa cornuta shown in fig. 26. Dorso-mesad of the processes be on the sixth tergite of Notiothauma shown in fig. 1, are two smaller processes (paired) which may have developed as enlarged "setigera" or seta-bearing protuberances of the segment. These setigera bear dinotrichia or powerful bristles like those shown on the seventh and eighth tergites in fig. 1,



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4 Psyche [March
*
but most of the set2 and bristles have been omitted in fig. 1, to avoid making the figure too complicated to show the more important structures readily.
The seventh tergite in Notiothauma bears a pair of re- markable tergal processes labelled be in fig. 1, which appear to correspond in a general way to the structures called the "bicornua" in the male Plecopteron shown in fig. 17, plate 2, of vol. 13 of the Bulletin of the Brooklyn Ent. Society for 1918, and this term has therefore been applied to the struc- tures labelled be in fig. 1 of Notiothauma. The "bicornua" of the seventh tergite in Notiothauma (be of fig. 1) appar- ently serve to support the genital structures when the tip of the abdomen is turned forward over the top of the abdo- men in the male insect. Since there are no such structures on the seventh tergite of the other Mecoptera I have ex- amined, it is possible that these remarkable processes are peculiar to Notiothauma among the Mecoptera. The abdominal segments (with the exception of the first) as far back as the eighth segment, in Notiothaurna, are "dis- c1eritous"-i. e., the tergal and sternal sclerites are distinct and separate (the tergites are denoted by the letter t and the sternites by the letter s in fig. 1)-and the spiracles labelled sp) are located in the pleural or lateral membrane between the tergites and sternites. The fulvous-colored eighth and ninth abdominal segments, however, are "syns- c1eritous"-i. e., the tergites and sternites have united to form a complete ring or continuously sclerotized surface from dorsal to ventral sclerite, and the spiracle of the eighth segment (which is larger than the preceding ones) is surrounded by the sclerotized surface, instead of being located in a pleural membrane.
In Panorpodes the eighth and ninth segments are syn- scleritous (tergites and sternites fusing completely) and the seventh segment is partially synscleritous, the fusion of the tergite with the sternite being complete in the an- terior half of the segment, but the posterior half retains a partial division between tergite and sternite. Panorpodes thus presents an intermediate stage between Notiothauma (in which only the eighth and ninth segments are syn- scleritous) and the Panorpidse in which the seventh, and



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19311 Structure of Notiothauma reedi 5
sixth segments also, are synscleritous. Panorpodes likewise presents an intermediate condition between the posterior abdominal segments of Notiothauma, which are broad and flattened, and the narrow more cylindrical segments of the postabdomen (narrowed region) of the Panorpidag, since the segments in Panorpodes are somewhat narrower than those of Notiothauma but are not as narrow as those of the Panorpidae, in the postabdomen. As was mentioned above the sixth, seventh, eighth and ninth segments are syn- scleritous in the Panorpidag; the sixth is discleritous, the seventh partially so, the eighth is synscleritous and the ninth is synscleritous in Panorpodes; the sixth and seventh abdominal segments are discleritous and the eighth and ninth are synscleritous in Nannochorista and Notiothauma. In Chorista and Merope the sixth and seventh abdominal segments are discleritous and the eighth and ninth are weakly so. In Boreus and Harpobittacus the sixth, seventh, eighth and ninth (reduced in Harpobittacus) abdominal segments are discleritous.
The ninth segment of the male has been termed the an- dromere (since it is the genital segment "par excellence") and the ninth segment together with the genitalia constitute the androecium, or as the Dipterists term it, the hypopy- gium. The andromere or ninth segment presents some in- tensely interesting modifications in Notiothauma. Its ter- gal region or epiandrium labelled ep in fig. 1, bears a re- markable median dorsal process
(labelled g in fig. 1 and
fig. 4) which is turned slightly forward. The lateral por-
tions of the epandrium on each side of the median process g are produced posteriorly to form two lobe-like projec- tions labelled e in figs. 1, 4, 5 and 37, and these epandrial processes bear lesser lateral projections as is shown in figs. 1 and 4 of Notiothauma. These epandrial processes are apparently homologous with the processes and lobes of the ninth tergite variously termed the surgonopods, sur- styli, epivalvse, epiprocessi, etc., in different insects. The condition exhibited by Notiothaurna, in which the epan- drium is produced posteriorly to form the epandrial lobes e above the anus-bearing structures pg of fig. 37, apparently



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6 Psyche [March
represents the starting point of the development of the epandrial processes and lobes of other Mecoptera. In Merope the epandrial processes e of fig. 36 are broad, flat, pointed plates clearly demarked from the tergite be- hind them.
In the Bittacidse represented by Harpobittacus (fig. 35) the epandrial lobes become highly developed, and in some Bittacidse they are extremely large and are pro- vided with roughened areas suggesting that they may play a part in mating (as claspers), and on this account they were referred to as the "copulalobi" in the Bittacidse, but it is preferable to designate all of these lobes and processes of the ninth tergite as the epandrial processes (or lobes). In Harpobittacus the first abdominal segment (which is provided with a huge spiracle) is very small, so that the ninth segment might be counted as the eighth if the true first segment were overlooked, but by counting the eight pairs of abdominal spiracles one can determine the cor- responding segments, even when the first segment has fused with the metathorax as in Boreus, and when there has been a fusion or suppression of segments, the spiracles furnish the clews for determining whether the fusion has been in the anterior or posterior region of the abdomen, since if there are eight distinct, spiracle-bearing segments in the abdomen when the number of segments has been reduced, it is evident that the fusion has occurred posterior to the eighth segment. In the Boreidae, the epandrial lobes e of fig. 33 are rather densely beset with small protuber- ances giving a roughened appearance to their dorsal sur- faces. The epandrial processes are not developed in Chorista (fig. 34) or Pawpodes (fig. 31) or most Pan- orpidse (fig. 31), and the character of the epandrium ep of Chorista and Panorpodes (figs. 34 and 31) points to a rather close relationship between these insects, and Panorpodes is apparently closely related to the ancestral Panorpidse among the Mecoptera. In Chorista and Panorpodes (figs. 34 and 31) the anus-bearing structure pg is not covered by the epandrium ep, but in the Panorpid shown in fig. 28, the epandrium ep is produced posteriorly and completely hides the proctiger beneath it.




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19311 Structure of Notiothcdumu reedi 7
The hypandrium or sternal portion of the ninth segment (andromere) is extremely interesting in Notiothauma- (i. e., ha of figs. 7 and 21), and its condition in Notiothuuma, might be taken as the starting point for tracing the modifi- cations of the hypandrium of other Mecoptera (see ha in the different figures), although the hypandrium ha of Chorista shown in fig, 18 might also be taken as the start- ing point in tracing the development of the hypandrium in other Mecoptera. The hypandrial processes labelled k in figs. 18, 21, etc., have been termed the hypovalvge, hypo- process!, etc., but in the following discussion they will be referred to simply as the hypandrial processes. In Notio- thaw (figs. 1, 7 and 21) the hypandrium ha (which is divided into a basal and distal area)
bears an unpaired
median process and two lateral processes, while in ChonSta (fig. 18) the median process is not developed, and there are small secondary mesa1 processes on the lateral hypandrial processes labelled h in fig. IS. In Merope (fig. 19) and Boreus (fig. 17) the hypandrial projections h are very slightly developed,
In Panorpodes (fig. 20), however, the
hypandrial processes h are well developed (and are pro- vided with peculiar outgrowths, as shown in fig. 20), and in the development of its hypandrial processes, Panorpodes approaches the Panorpidse more closely than any other lower Mecoptera do. In most Panorpidae, such as the one shown in fig. 22, the hypandrial processes are well devel- oped and in the Indian Panorpid shown in fig. 23, which has the moat peculiar hypandrium of any Mecopteron I have seen, the hypandrial processes h curve about a somewhat circular basal opening, and are produced posteriorly into elongated processes which are modified apically to form the peculiar distal structures shown in fig. 23. The hypandriurn is not prolonged posteriorly in the Bittacidae or Nanno- choristidae.
The male genitalia proper consist of the gonopods ex and st of fig. 13 and the structures comprising what the Dip- terists call the phallosome, made up of the valvee and other projections about the penis or the genital opening-i. e., the central structures labelled ps in fig. 13. It is very difficult to interpret the homologies of the male genitalia in the



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8 Psyche [March
different orders of insects, and the homologies of the parts in Diptera, Mecoptera, etc., are still in dispute. In a discussion of the male genitalia of Diptera, Mecop- tera, and related forms, published in Vol. 25, p. 47, of Psyche for 1918, the structures labelled st and ex in figs. 3, 7, 8, etc., were designated as the gonopoda; but in at- tempting to homologize the gonopods of sawflies (which are fundamentally like those of Diptera and Mecoptera, but are of a more primitive type) with the gonopods of male Ephemerids, etc., which have retained the parts in practically the original condition for insects in general (see Canadian Entomologist, Vol. 52, p. 178, for 1920), I was misled by the fact that the bilobed basal plate (called the "cardd' by Hymenopterists) of some sawflies' genitalia re- sembles the fused coxites in the male genitalia of certain mayflies and the two-segmented forceps of these sawflies resemble the styli of certain mayflies, in which the styli are composed of two or more segments. Using the condi- tion exhibited by these sawflies as the basis for determining the homologies of the parts in Diptera and Mecoptera, I consequently homologized the segment labelled st in figs. 3 and 7, of the Diptera and Meeoptera with the distal seg- ment of the stylus (i. e., with the dististyle) and homolo- gized the basal segment labelled ex with the basal segment of the stylus (i. e., with the basistyle), and interpreted the '
demarked basal areas of these basistyles as the reduced coxites in Diptera and Mecoptera (see also Vol. 48, p. 207, of the Transactions of the American Ent. Soc. for 1923). In his review of Dr. Alexander's "Craneflies of New York," however, Walker, 1920 (Canadian Entomologist, Vol. 52, p. 190), states that in the Diptera the distal portion of the claspers (i. e., st of fig. 3, represents the entire stylus, while the basal portion ex of fig. 3 represents the coxite instead of the basal segment of the stylus, and Eyer, 1924, (Annals Ent. Soc. of America, Vol. 17, p. 276) applies this interpretation to the Mecoptera and other Holometabola. Mr. R. E. Snodgrass, who has been making a detailed study of the musculature of the genital claspers, etc., of male in- sects, informs me that the musculature bears out the view that the basal segment of the gonopods (labelled ex in the



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19311 Structure of Notwthauma reedi 9
different figures) is the coxite, and the distal portion (st in the different figures) represents the entire stylus, so that I have provisionally adopted this view of the interpre- tation of the parts of the gonopods in the present paper. Mr. Snodgrass is inclined to regard the basal collar called the "cardo" in the genitalia of Hymenoptera, as a detached basal portion of the coxites, which has united with its fel- low from the opposite side to form a basal collar-like sclerite in these insects, while the basal segment of the (outer) claspers represents the remainder of the coxite, and the outer claspers themselves represent the styli, in the Hymenoptera, and this view seems to be as reasonable as any, since it is in accord with the evidence of the muscula- ture of the structures in question. It should not be for- gotten, however, that Emery, Wheeler, and other students of the ants, interpret the basal and distal portions of the outer claspers (i. e., the gonopods) as parameres, and the question of the homologies of the parts of the gonopods is by no means settled as yet. In the following discussion, I shall refer to the claspers st of figs. 3, 7, 8, etc., as the gonostyles, and shall designate the basal portions ex as the gonocoxites, terming them both together, the gonopods. The gonopods st and ex of Notiothauma (figs. 1, 6 and 7) not only furnish the prototypes from which the gonopods of the Panorpidee and other Mecoptera could be derived, but they are also surprisingly like the gonopods of primi- tive Diptera such as Trickocem (fig. 3), suggesting that the ancestors of the Diptera were very like Notiothaiima in the character of their genitalia. Thus, the gonostyle st of Trichocem bitubercdata Alex., shown in fig. 3, has a medio- tubercle m and a basitubercle & astonishingly like the me&- tubercle m and the bastitubercle 5 of the gonostyle of Notio- thauma shown in fig. 7, but I have not found any Dipteron in which the gonostyle (st of fig. 3) bears a peculiar stylorganus (or stylar organ) like that labelled o in the gonostyle st of Notiothauma shown in fig. 7, although such a stylar organ is not found in all of the Mecoptera either, being apparently absent in Chorista and Panorpodes (figs. 12 and 13) and in all of the Panorpidse and Bittacidse that I have examined. A styloxgan o is present in Notiothauma



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10 Psyche [March
(figs. 1, 5 and 7), in Merope
(fig. 13), in Nannochorista
(fig. 10) and in Boreus (fig. 9), however, and this may indicate that Notiothauma is very like the common ances- tors of all of these Mecoptera, since the ancestors of these forms must have had a stylorgan, if this structure is devel- oped in these families.
Aside from the presence of stylorgans o in both Notio- thauma (fig. 7) and Merope (fig. 16) the gonostyles st themselves are not very similar in the Notiothaymidse and Meropidse, since the gonostyli of Merope (fig. 16) are long and slender and resemble those of certain Chironomid Diptera in contour, while the gonostyli of Notiothauma are more like those of the Dipteron Trichocera bituberculata in contour, and it is amazing that the gonostyli of these closely related families of Mecoptera (the Notiothaumidse and Meropidse, should resemble the gonostyli of Diptera more than they resemble each other.
The gonostyli st of Notiothauma (figs. 5 and 7) are more normal, and therefore furnish better starting points for tracing the development of the gonostyles of other Mecop- tera than is the case in other primitive Mecoptera such as Chorista (fig. 12) in which the basitubercle b and the medi- tubercle m are modified in a peculiar manner, and the gono- style is not as much like those of Panorpodes (fig. 13) and the Panorpidse (fig. 23) as the gonostyle of Notiothauma is. The gonostyle st of the Indian Panorpid from Mysore, shown in fig. 23, is so astonishingly hairy that this remark- able Panorpid should be called "Panorpa hirsuta" if it should prove to be new to science, and an appropriate name is desired for it! The Panorpid shown in fig. 8 has remark- ably "thin," leaf-like gonostyli st with a peculiar basitu- bercle b and meditubercle m, and with a very peculiar mesa1 process en or "endostyle" which may represent the inner branch of the divided gonostyli in Diptera (i. e., the so-called inner basistyle in certain Diptera) . In comparison with the size of the coxites which bear them, the gonostyli st are rather short in the Boreidse (fig. 9) and Nanno- choristidse (fig. 10) ; and in the Bittacidse represented by Harpo bittacus (fig. 11) the gonostyli st become tremen-



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19311 Structure of Notiothauma reedi 11
dously reduced- feature which serves to set apart the Bittacidae from the rest of the Mecoptera very sharply. In Notiothuumu, the gonocoxites ex of figs. 6 and 7, are more like the prototypes of the gonocoxites of the Pan- orpidse (figs. 8, 23, etc.) than is the case in Chorista (fig. 12), although Chorista and Panorpodes are not sharply set off from the Fanorpidse in this respect. ID Notiothauma (fig. 5) there is an intercrater ec or intercoxal region which is hollowed out and sclerotized in a fashion suggesting the prototype of the condition met with in primitive Diptera, and all of the features of the genitalia of Notiothauma sug- gest that the ancestors of the Diptera resembled Notio- thauma in many respects.
In Boreus (fig, 9) the gonocoxites ex are quite large in proportion to the size of the gonostyles st, and there is a wide posterior, or ventral, intercoxd area ie of membrane between the gonocoxites ex. In Nannochorista (fig. 10) the gonocoxites ex are likewise very large in proportion to the length of the gonostyli st, but the intercoxal area has be- come sclerotized and the gonocoxites appear to be quite solidly united. In the Bittacidse (fig, 11) the intercoxal area has likewise become sclerotized, but a partial suture remains to demark the distal region of the gonocoxites, which are hugely developed in proportion to the size of the gonostyli st.
In the Panorpid shown in fig. 8, the posterior intercoxal area contains a pair of membranous lobe-like valves, the postvalvse labelled p in fig. 8. These are apparently homo-