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Home , Archescytinidae, Archodonata, Diaphanopterodea, Glosselytrodea, Miomoptera, Permopsocida

THE ORIGIN AND EVOLUTION OF HYMENOPTEROUS [p. 24] Chapter 3 EVOLUTION OF THE INFRACLASS SCARABAEONES A. P. Rasnitzyn*

Dragonflies [order ] and [order Ephemeroptera], which have retained a primitive thorax structure (absence of a cryptosternum) but are specialized in other respects, occupy the most isolated position in the infraclass. They are similar to each other in a number of characters, but the nature of the latter does not allow drawing a conclusion about any close relationship of the two orders. Indeed, the primitiveness of the structure of the thorax common to both of them, like any symplesiomorphy, is not evidence of a common origin. The adaptations of the larvae of mayflies and dragonflies to an aquatic way of life are different, and they show, rather, an independent transition to development in water. The loss of the ability to fold the wings as well is connected with different processes in them: in mayflies, with the ephemerality of the imago, the function of which is essentially limited to nuptial flight and oviposition; and in dragonflies, with the metamorphosis of the adult to an active aerial predator. It is highly probable that mayflies and dragonflies are independent evolutionary branches. The belonging of dragonflies and mayflies to a common trunk of Scarabaeones, that is, the isolation of them from Protoptera as part of a single trunk with the remaining members of the infraclass (except Protoptera), is confirmed by the metamorphosis of the style of the ninth segment in males into part of the copulatory organ [endophallus], and in dragonfly females into a sheath of the ovipositor. The ovipositor in mayflies is reduced; it is unknown what function the styles in females of their ancestors performed, but the very fact of the coincidence of their reduction with the reduction of the ovipositor is indirect evidence of the advantage of the transition of styles as part of the ovipositor, that is, of the similarity of mayflies to dragonflies and higher Scarabaeones as

* Original citation: Rasnitsyn, A. P. 1980. Proiskhozhdenie I evoliutsiia pereponchatokrylykh nasekomykh. Trudy Paleontologicheskogo Instituta, Akademiia Nauk SSSR (Transactions of the Paleontological Institute, Academy of Sciences of the USSR) 174:24–35. Translated by Rosanne D’Aprile Johnson; scanned and edited by Abree Murch and Matthew Carrano, Smithsonian Institution, 2014. Brackets [] indicate comments added by original translator. well, according to this character. In an analogous way, the reduction of the primary copulatory organ of dragonflies does not allow judging its initial structure. However, the approximated laying of the anlagen (Makhotin, 1934), typical of most Scarabaeones (except mayflies) and correlating with the distinguishing of the isolated, variably mobile genital capsule in them, points to a similarity of dragonflies (even deeper than in mayflies) to higher Scarabaeones. This allows proposing that dragonflies were separated from the common trunk of the infraclass even later than mayflies. Additional evidence of the same is the later appearance of ocelli [simple eyes] in dragonfly ontogeny, as in and Oligoneoptera, but unlike bristle-tails, mayflies and , in which the ocelli already appear at the first postembryonic stage (see Fig. 3). Both dragonflies and mayflies deserve being distinguished into special cohorts, corresponding to Libelluliformes and Ephemeriformes. As has been mentioned, the former are known from the late Namurian and are the most ancient of the now-surviving orders of insects. In spite of their presumably earlier isolation, mayflies really appear only in the Late . This fact does not compulsorily point to the incompleteness of the geological record: it is quite possible that, for example, the ancestors of mayflies only acquired characters typical of the order toward this time. Insects with complete metamorphosis, the cohort Scarabaeiformes (= Oligoneoptera), form a restricted group within Scarabaeones. A sharp differentiation of ontogeny at the stages of primary morphogenesis (egg and chrysalis), feeding and growth (larva), and reproduction and settling down (imago) (Rasnitsyn, 1965a), is characteristic above all. At that, the degree of embryonation of ontogeny (adultization of the first postembryonic stages), minimal compared with that among contemporary pterigotes, is observed only in mayflies. Of the morphological characters common for the imagines of all Scarabaeiformes, it is possible to indicate perhaps only the appearance of the third medial articulation of the middle and posterior coxae with the thorax. The composition and structure of the cohort is discussed later. Two large groups, Paraneoptera and Protorrhynchota, are distinguished among the remaining Scarabaeones. The first, including Psocopteroidea, [p. 25] Thysanopteroidea, and Homopteroidea1, was distinguished by Martynov (1925) as one of three subsections

1 are often attributed to Paraneoptera; however, even the most important characters of similarity of Neopter. The cohort Protorrhynchota was established by B. B. Rohdendorf (1968) for orders of that were grouped around . Besides this order, it includes , , and as well, and was contrasted by Rohdendorf with cohort Hydropalaeoptera (Ephemeroptera + Odonata). The basis for distinguishing Protorrhynchota is the structure of their mouth parts, transformed into a pricking-suctorial proboscis. Rohdendorf believed the proboscis structure of Protorrhynchota and Homopteroidea to be identical, and proposed that protorrhynchots were direct ancestors of Homopteroidea, and with them of all paraneopters as well. Objections were advanced against Rohdendorf’s hypothesis (Sharov, 1973), based on existing differences in proboscis structure (in Homopteroidea, the stylets are protected by a sheath from the labium; in Thysanopteroidea, from the labrum; in Protorrhynchota, they are protected only by maxillary palps, and, at least in Diaphanopterodea, by labial palps as well), and on the absence of a proboscis in book lice [order ]. The direct descent of all paraneopters from protorrhynchots is really scarcely possible. The opposite hypothesis, of the origin of protorrhynchots from rhynchots, is unacceptable as well, because the most primitive representatives of the latter (Archescytinidae) already possess a specialized proboscis, and in addition appear much later than protorrhynchots (in the ). Nevertheless, the phylogenetic connection between protorrhynchots and paraneopters is highly probable, supported by many structural features of the order Hypoperlida. The Hypoperlida forms a diverse and probably rather extensive group of Paleozoic insects that possess characters of advanced Scarabaeones (thorax with a cryptosternum, primarily roof-shaped wing-flexing, posterior wings without bending the anal lobe, ovipositor with sheaths) and display definite connections with Paraneoptera and Protorrhynchota (the tendency toward lengthening the head and mouth parts, which is realized in the shape, similar in detail to that observed among Permian book lice, and which it is possible to regard as an intermediate stage in the formation of the proboscis of of these insects with Paraneoptera (decreased number of Malpighian tubes, free ganglia of the nerve cord, and segments of the tarsi) (see Kristensen, 1975) are not more reliable than those that unite them with Polyneoptera (first of all, the structure of the lower side of the thorax, and in particular the absence of a cryptosternum). On the other hand, not all characters that distinguish Zoraptera from Paraneoptera in Kristensen’s view (1975), are such (ocelli are developed in the nymph of not only Zoraptera, but also Paraneoptera, for example in the late nymphs of Cicadidae). The question of the position of Zoraptera within the insect system needs additional analysis. protorrhynchots). The central family of the order Hypoperlidae (Rasnitsyn, 1977a) is truly known starting in the Late Carboniferous (Fig. 11), but it reaches a special diversity in the Permian (Figs. 12–16), the described forms far from exhausting the material collected from the group. Hypoperlids were described among Paraplecoptera (Martynov, 1928), but Sharov (1961) noted their sharp distinction from both Paraplecoptera2 and , and indicated the need for a revision of their systematic position. Many members of the family (Dinopsocus Martynov = Martynopsocus Karny, Kaltanelmoa Rohdendorf, Fatianoptera O. Martynova) were described as special families in different orders of insects (Psocoptera, Diaphanopterodea, and Raphidioptera, respectively), but at least for Martynopsocus, its similarity to Hypoperlidae has been mentioned (Sharov, 1961). True finds of hypoperlids outside the U.S.S.R. are not known, but it is quite possible that some Carboniferous insects belong to them, including also the Namurian of Europe and North America, especially Ampeliptera Pruvost (Fig. 17) and Aenigmatodes Handlirsch (Fig. 18). Also other Carboniferous insects, which were partially mentioned above in connection with the order Protoptera, could turn out to be close to hypoperlids: Limburgina [p. 26]

2 Subsequently Protoblattodea (Sharov, 1968).

Figs. 11– 16.

Representatives of the Family Hypoperlidae. 11 – Tshunicola carbonarius A. Rasn.; Upper Carboniferous of the Tungusskiy Basin; 12 – Hypoperla elegans Mart.; Upper Permian of the Arkhangel’sk Region; 13 – Martynopsocus arcuatus (Mart.); Upper Permian of the Arkhangel’sk Region; 14 – Hypoperlopsis splendens G. Zal.; Lower Permian of Priural’ye: a = general view, b = head; 15 – Fatianoptera mnemonica O. Mart.; Lower Permian of the Tungusskiy Basin; 16 – Tshekardobia osmylina A. Rasn.; Lower Permian of Priural’ye; reconstruction. (11 – from Rasnitsyn, 1977a, 16 – original [p. 27] drawing of A. G. Ponomarenko; 12–15 – original: 12 – Solana, a – Specimen 117/968, b – 117/2285; 13 – Soiana: a – 117/2187, b – 3353/459; 14 – Chekarda, a – Specimen 1700/3298, b – 1700/1880; 15 – holotype).

Figs. 17–19. Insects that are being brought together with Hypoperlidae. 17 – Ampeliptera limburgica Pruvost; Lower Carboniferous of Holland; 18 – Aenigmatodes danielsi Handl.; Middle Carboniferous of the U.S.A.; 19 – Protoprosbole straeleni Laur.; Lower Carboniferous of Belgium; (17 – from Kulakova, 1958; 18 – original drawing of A. G. Sharov from photographs of the holotype; 19 – from Rohdendorf and others, 1962).

Fig. 20. Permopsocus latipennis Till., book of suborder Permopsocida; Lower Permian, U.S.A. (from Tillyard, 1926).

Laurentiaux, Protoprosbole Laurentiaux (Fig. 19), Metropator Handlirsch (see Fig. 10), “Mixotermitoidea”, Pseudohomotethus Handlirsch, Climaconeura Pruvost, Emphyloptera Pruvost, Hapaloptera Handlirsch (see Fig. 9). The overall appearance is characteristic of hypoperlids, similar to that of and —a light, well-proportioned body, membranous roof-shaped wings, homonomous in form but with typical heteronomy of venation, partially inherited from Protoptera of the type of Evenkia and practically identical to so many insects with complete metamorphosis (especially ). In the anterior wings, RS comes out from R much more distally than in the posterior ones, CuA is sharply convex, and CuP is very sharply concave, whereas in the posterior ones, CuA is distinctly concave, although sometimes also situated at the convex fold of the membrane, and CuP is almost neutral (perhaps due to fusion with anterior branch A). RS normally is strictly pectinate backward, usually with 3–4 branches. M is free (not fused at the base with CuA), usually with 2–4 branches; as a rule, it begins to branch late; with 3 limbs, it is pectinate forward, with 4 dichotomous branches. M5 in the form of a typically short and oblique, more rarely transverse, vein between M and CuA. CuA has a short bifurcation (sometimes with three limbs). CuP is simple or branching in front of the apex. The anal veins are not numerous. The antennae and legs are thin and long. The head is not large, with gnawing mandibles and possibly elongated baculiform laciniae of the maxillae (Fig. 14b). The pterothorax is homonomous. The ovipositor is sharp; the sheaths form a third of its valve (see Fig. 16). The structure of the male genital organs is unknown. The cerci are short and uniarticulate. Ecologically, hypoperlids are assumed to have been plant-dwellers that retained trophic connections with the generative organs of plants. In their characters, hypoperlids are very close to primitive paraneopters, in particular to book lice. Especially striking is the similarity of venation in several representatives to Permian Psocidiidae (Fig. 20). It is very possible that hypoperlids were direct ancestors of book lice and their kin, and of all Paraneoptera as well, especially taking into account the greater antiquity of hypoperlids. True Carboniferous paraneopters are not known; the membership of Protoprosbole Laur. in Jugatae is doubtful, as well as two other Carboniferous insects described in this capacity, Archeglyphis Mart. and Blattoprosbole B.-M.; the latter is a apparently (Sharov, 1966a). Archeglyphis is known from a single poorly preserved impression that does not display a clear resemblance to Jugatae, but Protoprosbole, judging from venation, is very close to Hypoperlidae. If the assumption about the elongated baculiform laciniae of Hypoperlidae is confirmed, the close connection of this group to paraneopters will become practically unquestionable. In spite of the very probable proximity of hypoperlids to book lice and their kin, to place them not only in this order but also in the “Paraneoptera” group itself is scarcely reasonable. The most characteristic trait of the evolution of paraneopters is their transition to an increasingly complete parasitism on plants with feeding primarily on the generative organs (book lice of suborder Permopsocida with a beak-like, elongated head, Vishniakova, [p. 28] 1976; [order Thysanoptera], also until now feeding on , see Grinfel’d, 1962; primitive Jugatae of the family Archescytinidae, whose unique ovipositor structure compelled Bekker-Migdisov, 1972, to propose for them oviposition in young cones of Gymnospermae, from which the larvae hatched after their dehiscence). Only subsequently did paraneopters turn to feeding on the vegetative organs of plants (sometimes later to predation) or to mycophagy (present-day book lice and their kin). In accordance with the feeding specialization, to some degree or other flight would play a role (as compensation, the ability to jump often appears), and correspondingly the general appearance changed: in book lice, the body has become more compact and stocky, and it is preserved that way in most paraneopters. Namely, it also seems more logical to draw the boundary-line of paraneopters within the transition to a less mobile way of life. The presence of cerci in hypoperlids and their absence in paraneopters can serve as the formal diagnostic character. If the presence of baculiform laciniae in hypoperlids is accepted as an established fact, and the boundary-line of paraneopters is drawn according to the appearance of this character, then apparently protorrhynchots must also be included in the same group of paraneopters, which probably inherited the elongated laciniae from the common ancestor with hypoperlids. There is indisputable sense in this union, and the boundary between this large group (including even some other orders discussed later) and the rest of Scarabaeones is sharper than anywhere within it, and corresponds more to the boundaries between cohorts. It is possible to accept this group (Paraneoptera + Protorrhynchota + Hypoperlida, etc.) as a single cohort, Cimiciformes, but it would differ very much from paraneopters as Martynov understood them. The vast gap between hypoperlids and protorrhynchots is to a definite degree filled by the families Synomaloptilidae, Strephocladidae and close groups (Tococladidae, Nugonioneuridae, Permarraphidae), and possibly Homeodictyidae. In the first family, Synomaloptila Martynov (Fig. 21) has rather similar venation to Hypoperlidae, but the overall appearance is different, as it is also in other members of the family (Figs. 22–24). The dimensions are large, the body long but relatively heavy; the wings are long and fold flatly on the abdomen. The legs are powerful, held fast as in many that inhabit plants (femurs with dentes, the segments of the tarsus are broadly bilobate, the tarsal claws are large; unlike beetles, a huge arolium is developed). The head is very elongate and beak-like, pointed in front; narrow and long, almost stiletto-like mandibles, crenate along the inner edge, form the apex of the “beak.” The maxillae also form part of the “beak” (by analogy with book lice, probably their laciniae). Unlike hypoperlids, here these structures are already certainly very much more hypertrophied, and they form almost stiletto-like structures, but jagged on the inner edge and forked at the base; the structures occupy more than half the length of the head. Judging by the structure of the head and legs, synomaloptilids probably inhabited plants and fed by eating away the contents of gymnosperm ovules (Rasnitsyn, 1977a). Sharov (1973) suggested an analogous method of feeding for protorrhynchots, with the difference that there was a genuine pricking-suctorial proboscis in the latter, and they must not have been gnawing out ovules, but rather sucking them out, and consequently taking advantage of younger, immature ovules. According to the way of life and structure of the head, synomaloptilids would have been able to claim the role of protorrhynchot ancestors, but this is hindered in the first place by the flat wing-flexing, from which it is impossible to deduce a roof-shaped flexing characteristic of Diaphanopterodea, and in the second place by the later (Permian) appearance of the family in the geological record. The first of these obstacles is removed by the family Permarrhaphidae (= Strephoneuridae syn. nov.)1, similar to Synomaloptilidae in the [p. 29]

Figs. 21–25. Representatives of the Order Hypoperlida from the Lower Permian of Priural’ye, families Synomaloptilidae (21–23), Permarrhaphidae (24), and Perielytridae (25).

1 Permarrhaphus venosus Martynov, from the Late Permian of the Kama River, was described as a wing- case of a (Martynov, 1930); later, A. G. Sharov observed that this is simply a torn-off clavus (the anal region of the anterior wing) of an insect, close to Strephoneura Martynov. Unfortunately, these data were not published.

21 – Synomaloptila longipennis Mart.; 22 – Rhinomaloptila polyneura A. Rasn.; 23 – Mycteroptila dina A. Rasn.; 24 – Strephoneura robusta Mart.; 25 – Perielytron mirabile G. Zal.: a – body and posterior wing, b – anterior wing (21–23 from Rasnitsyn, 1977a, 24–25a – original, combined drawings of the following specimens: 24 – 168/12, 1700/3375, 3376; 25a – 1700/1863, 1864, 4656; 25b – from Rohdendorf and others, 1962). structure of the head and legs (femurs with dentes, tarsi with powerful tarsal claws, and arolia), but retaining a roof-shaped wing-flexing. The venation is very different from that of Synomaloptila Martynov, but more similar to the venation of other Synomaloptilidae. It is essential that the posterior branch M of permarrhaphids is distinctly concave; the same feature is expressed less clearly in Mycteroptila as well. It is possible to consider [p. 30] the concave MP of protorrhynchots as analogous. Here the anterior branches of M are neutral, unlike the MA of protorrhynchots; the subsequent differentiation of median branches to the convex MA and concave MP takes place in Late Permian Homoeodictyidae (Table II, Fig. 6), the systematic position of which is obscure, but proximity to Synomaloptilidae and Permarrhaphidae is not ruled out. Permarrhaphidae have one more character that unites them with palaeodictyopteroids: not long but clearly segmented cerci. Such cerci could fully be predecessors of long caudal setae, characteristic of palaeodictyopteroids (Fig. 26–27). It may be observed in passing that in Diaphanopterodea, unlike Palaeodictyoptera and Megasecoptera, males apparently lacked caudal setae (anal filaments), finely developed in females; in any case, this is supported by extensive Early Permian diaphanopteroid materials in the collections of the Paleontological Institute of the Academy of Sciences of the U.S.S.R. As has been noted, cerci are short and uniarticulate in hypoperlids. The later appearance in the geological record, mentioned above as an obstacle for inferring protorrhynchots from synomaloptilids, is also justified for permarrhaphids, known only from the Early and Late Permian of Priural’ye and Prikam’ye. The chronological gap between the Early Permian and the appearance time of palaeodictyopteroids (early Namurian) is partly filled by a family with similar wing venation, Strephocladidae (other body parts are not known, but in a close family, Tococladidae, the structure of the head is evidently close to that of permarrhaphids, see Carpenter, 1976). Except for finds mentioned in the literature (in the Late Carboniferous of the Federal Republic of Germany, and the Early Permian of the Czechoslovak Socialist Republic and the U.S.A., see Carpenter, 1966), there are also undescribed forms of strephocladids in the Late Carboniferous of Brazil (“Narkemidae sp. C,” Pinto, 1972) and the Late Permian of the Arkhangel’sk Region (data of the author). True, the temporal hiatus, including the Namurian and Middle Carboniferous, also remains highly significant with regard to them, but many insects of obscure systematic position are known from this time, related to palaeodictyopteroids only in the structure of the wings. By taking into account the diversity of venation in synomaloptilids, permarrhaphids, and strephocladids, it is quite possible that some of the known Namurian and Middle Carboniferous insects will, when more complete remains are found, turn out to be representatives of the same group of the order Hypoperlida that is proposed here as ancestral to palaeodictyopteroids. Thus, the families Hypoperlidae, Protoprosbolidae, Synomaloptilidae, Permarrhaphidae, Strephocladidae, Tococladidae, Nugonioneuridae, and Perielytridae (Fig. 25), earlier separated in a special order Perielytrodea (Zalesskii, 1948), are included in the order Hypoperlida with variable degrees of confidence. The taxonomic position of Homoeodictyidae, Mixotermitodea, Hapalopteridae, Aenigmatodes, and other forms discussed above seems less definite. Besides hypoperlids, paraneopters, and protorrhynchots, the order Blattinopseida with the sole family Blattinopseidae should also be brought into the cohort Cimiciformes. Blattinopseids (Figs. 28–29) have always been considered to be among Polyneoptera in the orders Protoblattodea or ; only A. G. Sharov (1968) demonstrated the need to reexamine their systematic position. Blattinopseids range from the Middle Carboniferous to the end of the Permian as well. The body and wing structure, studied in the extensive material of the Glaphirophlebia from the Lower Permian deposits of Priural’ye and the Upper Permian of the Arkhangel’sk Region, shows that these are undoubtedly Scarabaeones, close in morphological level to Cimiciformes and Scarabaeiformes but manifestly not related to the latter due to the absence of complete metamorphosis (see Laurentiaux, 1959). In blattinopseids, the cryptosternum, the sharp ovipositor with sheaths, and the rather short, segmented cerci were developed. The mouth parts are gnawing, not elongated. The structure of the laciniae is unknown. The wings flex in a roof-shaped manner, the anterior ones were often visibly thickened, and in the posterior wing, part of the anal region (behind the two first, strongest anal veins) was not only slightly expanded, but also bent upon wing-folding, as in Homoptera, Auchenrrhyncha, bugs, and many insects [p. 31] with complete metamorphoses (especially beetles and ). The structure of RS and CuA of the anterior and posterior wings were distinguished in the same manner as in hypoperlids.

Figs. 26–27. Reconstruction of Palaeodictyoptera (26) and Diaphanopterodea (27) (original drawing of A. G. Ponomarenko).

The venation of blattinopseids was very varied in details, but also similar in appearance with a series of obvious specializations (the tendency toward having tectorial wings, expansion of the subcostal field, transition of branches M on RS, expansion and differentiation of the anal field of the posterior wing), but on a rather archaic basis, being displayed in the retention of M5, backward-directed pectin of the branches of CuA, and the characteristic heteronomy of the wings in the structure of RS and CuA. The important value of blattinopseids for phylogeny consists in the fact that their peculiar body structure corresponds to the evolutionary stage of Scarabaeones that could serve as the initial origin of both Cimiciformes and Scarabaeiformes (insects with complete metamorphosis). Indeed, they had already acquired a cryptosternum but still retained incomplete metamorphosis, segmented cerci, a primitive ovipositor, roof-shaped wing-flexing, and short mandibles, which are indirect evidence that changes in the direction typical for Cimiciformes in other areas of the mouth parts as well had probably not yet occurred. Ecologically, blattinopseids also were quite able to remain similar to their ancestors—protopters, that is, to keep the connection with plants and eating their generative parts. The presence in them of veins that pass along the posterior edge of the anal region in the anterior wing could be highly essential for resolving the question of the connections of blattinopseids. The point is that this vein, characteristic of the most Cimiciformes and many Scarabaeiformes, especially more primitive ones, plays a definite role in fixation of the wings in a resting position (often perhaps not as much in mechanical fixation, as in control of wing position). The posterior edge of the anterior wing at rest lies on the sides from the scutellum of the mesonotum and further back onto the surface of the metatergum, passing primarily approximately [p. 32]

Figs. 28–32. Representatives of the superorder Caloneuroidea, orders Blattinopseida (28–29) and Caloneurodea (30–31), and a family incertae sedis, Sypharopteridae (32).

28 – Glaphirophlebia uralensis (Mart.): Lower Permian of Priural’ye; a – general view, b – reconstruction; 29 – G. subcostalis (Mart.); Upper Permian of Eastern Europe; wings; 30 – Paleuthygramma tenuicornis Mart.; Lower Permian of Priural’ye; 31 – Caloneura dawsoni Brongn.; Upper Carboniferous of France; 32 – Sypharoptera pneuma Handl.; Middle Carboniferous of the U.S.A. (28a – original of Chekarda, Specimen PIN No. 1700/3361, wings from the holotype; 28b – original drawing of A. G. Ponomarenko; 29 – original of Soiana, Specimen PIN No. 3353/199, 203; 30 – original of Chekarda, Specimen PIN No. 1700/1437; 31 – from Carpenter, 1961; 32 – from Carpenter, 1967)

[p. 33] along the boundary of the scutum with the praescutum and scutellum. In book lice and many Scarabaeiformes, including apparently Miomoptera, one wide or two narrower, approximately parallel, impressions are formed here, in which this vein lies as well. In Homopteroidea, the fixation apparatus is shifted secondarily to the mesothorax, where two narrow, deep grooves are formed on the sides of the scutellum, in which the corresponding sections of the posterior margin of the anterior wings are enclosed. In neuropteroids, modern Meropeidae (Mecoptera), and the lowest Hymenoptera, rough fields are found independently on the metatergum and on the wing at the sites of contact (Riek, 1967: Rasnitsyn, 1969: Hlavac, 1974: Eichele and Villiger, 1974). In [Tricoptera], the rough edges of the field are usually developed only on the wings, in connection with the fact that the principal fixation here passes between the posterior edges of the anterior wings, which are superimposed on each other on the section freed from the anal veins verging on the edge of the wing (an adaptation to the hatching of the chrysalis in water; Sukacheva, 1976). However, the role of the metatergum in wing fixation is not completely lost, because its central part remains pressed in and usually edged with distinct rises; often, a similarity of the rough fields is also observed—true, very slightly marked. In connection with the described changes, the vein bordering the base of the posterior margin of the anterior wing probably disappears in Hymenoptera and caddisflies (as well as butterflies). The rough fields of Neuroptera often are ascribed a stridulatory function (Riek, 1967; Eichele and Villiger, 1974), which seems to be unlikely, above all because of the extremely extensive distribution of these formations, the absence of sexual dimorphism in their structure, and because of the fact that their structure (fields of spines or setae directed toward each other) is not characteristic of sound organs. However, even if it would be shown that the rough fields could really function as stridulators, it is doubtful that this would be their only function. In any case, experiments on unilateral amputation of the part of the wing of Chrysopa spp. and Hemerobius spp. bearing a rough field, unlike the data of Eichele and Villiger (1974), revealed the influence of amputation on the position of folded wings. First, the closing of the posterior margins of the wings became less tight; second, the fixation of the operated wing lost its former precision and stability: if in the vertical position of the body, the wings are situated at the same level, then in a horizontal one, the damaged wing sags somewhat. The removal of other parts of the posterior edge of the wing does not have an influence on its resting position. In Hymenoptera and in the Mecoptera Merope Newm. and Austromerope Kill. (Meropeidae), a subsequent change of the rough fields occurred with the formation of specialized coriaceous juga. In lower Hymenoptera, these juga, named cenchry, appeared on the scutellum. In Meropeidae (only in modern ones, but it is necessary to bear in mind that forms also differ from them in many other characters, so that attribution of them by Ponomarenko and Rasnitsyn, 1974, to this family may be erroneous), they are on the posterior edge of the wing. In the first case, the surface of the jugum became scaly, in the second, costate, like the surface of the rough field of the metatergum (Hlavac, 1974). Among Polyneoptera, only the groups most specialized in the direction of having tectorial wings (, [Dermaptera], brachycerous ) use the posterior-basal margin of the anterior wing for fixation. At that, because of the wider overlapping of the wings, the fortified margin of the wing is enclosed in an impression not on the metatergum, but rather on the mesonotum. In such groups, such as stone [Plecoptera], praying mantids, and termites (including Mastotermitidae), a similar fixation apparatus is not developed. All this says, is that in Polyneoptera, the means of fixation of folded wings, partly analogous to that of Cimiciformes and Scarabaeiformes, arose independently (and apparently repeatedly) from them, and the similarity of the two latter groups in respect to this character can turn out to be inherited from the common ancestor. What has been said above, of course, does not mean that Blattinopseidae, with their specialized venation, could have been the ancestors of Cimiciformes or Scarabaeiformes. However, the discussion is not about the family itself, but rather about a broader classification, other members [p. 34] of which could fully turn out to be primitive as well with respect to venation. True, the hope is not great that they will be found among existing materials, although the presence of them there seems quite probable. Such insects scarcely could be identified for certain, except in series that contain remains of the body in good, undamaged condition, a condition quite difficult to fulfill for Carboniferous insects, the most promising in this respect. Here it is only possible to observe that the venation of Middle Carboniferous Glaphyrocoris Richardson and Late Carboniferous “Blattinopsis” of the subgenus Stephanopsis Kulakova, described as blattinopseids, as well as Middle Carboniferous Protoblattinopseidae, is more primitive and at the same time displays certain features of similarity with typical blattinopseids. They indeed could be quite primitive representatives of that order. Blattinopseids, as has already been noted, do not provide grounds for assuming the isolation of laciniae in them, typical for Cimiciformes. Hence, the introduction of them into this cohort, depriving Cimiciformes of a single synapomorphy, can be assessed as artificial and arbitrary. However, given the scanty knowledge about this group, distinguishing blattinopseids into a special cohort, which we are now arranging, seems to be even more debatable. Hence, it is necessary to settle on the first of two possible solutions and to include blattinopseids as a special superorder in the cohort Cimiciformes. Besides blattinopseids and forms brought together with them, a similar position not far from the roots of Cimiciformes and Scarabaeiformes is occupied by one more Paleozoic group: the order Caloneurodea (Figs. 30–31), known from the Middle Carboniferous (family Genopterygidae) to the end of the Permian. Comparatively long wings are characteristic of Caloneurodea, externally similar to the wings of Synoptila (because of which the latter was also described among Caloneurodea, see Martynov, 1918), but they are completely homonomous, with a characteristic tendency to form a pair of straight, approximated veins in the middle part of the wing, and often with well- disposed transverse veins. In Carboniferous Caloneurodea (Caloneura Brongniart, Stenarocera Brongniart), the wings were flexed into a roof-shape: in Permian ones, flatly. The head and mouth parts are often short: baculiform laciniae, as in blattinopseids, have not been successfully discovered; probably, the laciniae retain a primitive structure. The thorax with a cryptosternum, and genital organs of both sexes, correspond to the morphological level of Cimiciformes. Ecologically, Caloneurodea apparently presented the life-form of stick insects [phasmids], similar not only the overall appearance and proportion of the limbs, but also the manner of arrangement of the transverse veins on the wings and even the structure of the eggs. On one of the impressions of Paleuthygramma tenuicorne Mart. from the Lower Permian deposits of Priural’ye, 19 large, rigid eggs, fortified with longitudinal thickenings, are visible in the abdomen of a female (Table III, Fig. 7). Of course, the similarity to stick insects is far from complete. Judging by the shortened and somewhat reduced ovipositor (but nevertheless considerably better- developed than in stick insects), and by the small number of eggs, Caloneurodea did not drop their eggs on the ground, but probably stuck them to a plant surface or concealed them in root cracks, leaf axils, or cuts made by the ovipositor on plants. The absence of reliable indications of phyllophagy in these, as well as any other Paleozoic insects1, makes it more probable that they fed not on leaves, like stick insects, but rather on the generative parts of plants, like many insects contemporary to them. Caloneurodea were considered to be among Polyneoptera until Sharov (1966b) transferred them to Oligoneoptera and included them, together with , in Neuropteroidea. If Glosselytrodea are indeed connected by a comparatively smooth transition with Neuroptera (see below), then no definite evidence of proximity to insects with complete metamorphosis has been successfully discovered for the order being discussed. Sharov convincingly demonstrated that Caloneurodea is not Polyneoptera (doubts that they are not related to either palaeopters or paraneopters [p. 35] have arisen as well), but this still does not demonstrate their belonging to oligoneopters (that is, Scarabaeiformes). For the moment, highly specialized and more ancient than insects with complete metamorphosis, any definite traits of similarity with the latter have not been revealed in this group; it is more reasonable to consider Caloneurodea to be among primitive Cimiciformes. The absence in them of any traces of changes of the mouth parts in the direction typical of Hypoperlida and their probable descendants, allows removing caloneurods from that hypothetical group of initial Cimiciformes, which were ancestors of both higher, typical representatives of the cohort and blattinopseids, and to unite them with the latter in one superorder Caloneuroidea. The structure of the mediocubital region of their wings serves as an additional argument in favor of the very early isolation of Caloneurodea. As has been mentioned, the presence of two approximated veins in the middle part of the wing is characteristic for the order. The anterior of them is convex, the posterior one is concave, which, it would seem, allows homologizing them correspondingly with CuA and CuP. However, behind them is situated one more concave vein, which is united at the base with the foregoing, and only the following vein occupies a convex position (all this is seen well on the wings of the most ancient caloneurods— Genopterygidae, see Richardson, 1956, Figs. 24–25). Obviously, we are dealing with a

1 An indication of a find of gnawed leaves of Paleozoic plants (Plumstead, 1963) exists, but proof of biting marks by insects, and not by diplopods, is absent. free M5, later with CuA, not united with M5 and hence retaining a concave position, as in the posterior wing of Evenkia, and with a concave CuP, as usual. As a group, allowing closeness with Caloneurodea, it is necessary to mention Middle Carboniferous Sypharopteridae (Fig. 32). Various authors have depicted their kinship ties in quite different ways (Carpenter, 1967a), and in the last work mentioned, the family is simply attributed as a group to insects of obscure systematic position. The venation of fully homonomous wings of Sypharoptera Handlirsch recalls the venation of caloneurods; however, here there are no approximated veins (on the other hand, they are also not always clearly marked in caloneurods themselves, for example in Permian

Permobiella Tillyard); probably there is no free M5, but it is impossible to speak confidently about this, because on the sole impression, the veins behind a supposed CuP have not been preserved. The position of the wings on the impression is more likely evidence of their roof-shaped flexing.