Jarmila Kukalová-Peck.
Unusual Structures in the Paleozoic Insect Orders Megasecoptera and Palaeodictyoptera, with a Description of a New Family.
Psyche 79:243-268, 1972.

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UNUSUAL STRUCTURES IN
THE PALEOZOIC INSECT ORDERS
MEGASECOPTERA AND PALAEODICTYOPTERA,
WITH A DESCRIPTION OF A NEW FAMILY*
BY JARMILA KUKALOVA'-PECK
Department of Geology, Carleton University, Ottawa, Ontario, Canada
The order Megasecoptera is a representative of the haustellate paleopterous insects of the evolutionary line that lived during the Pennsylvanian and the Permian. The similarity of wings and body structures, such as mouth-parts and genitalia, indicate very close re- lationship with the order Palaeodicty~~tera. Both groups are pre- sumed to have emerged sometime during the Mississippian from a common ancestor. While Palaeodictyoptera are usually larger and more sturdily built, bearing broad wings with a rich venation and prothoracic lobes, Megasecoptera are slender insects with a more delicate appearance, with petiolate wings and simplified venation, with enlarged thorax lacking prothoracic lobes, and with tapering abdomen.
The present paper deals with an extraordinary morphological feature - projections of the body cuticle, which occur in most or all Megasecoptera and at least in some Palaeodictyoptera. These are conspicuous processes, which are short to very long, simple or branched, and which are distributed in regular rows on the ab- domen and thorax.
A fuller understanding of the morphology of this very unusual character resulted from two years of intensive research by Dr. 3'. M. Carpenter and myself, based upon fossil material of Commentry (Upper Pennsylvanian, France), Mazon Creek (Middle Pennsyl- vanian, Illinois), Obora (Lower Permian, Czechoslovakia), Elmo (Lower Permian, Kansas), and now also Tshekarda (Lower Per- mian, Siberia). I am deeply indebted to Professor Carpenter, who was very helpful in the preparation of this study. Until now, the projections have been only poorly known. They were at first mostly interpreted as tracheal gills that persisted into the *This study has been supported in part by grant No. GB-27333 (F. M. Carpenter, Principal investigator, Harvard University) from the National Science Foundation.
Manuscript received by the editor July 15,1972. Pnrfif 79:MJ-268 Mil}. http://psyche cnlclub w@9#Μφ html



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244 Psyche
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adult stage, or later as short lateral spines on the abdominal segments and thorax. The following is a short account of present knowledge. The projections on the ~rothorax are, in some families, long and filiform, but in other families rather short, pointed and spine-like. They were described as spines in some Megasecoptera, namely in Mischoptera, Aspidothorax, Corydaloides and Foriria by Brongniart ( 1885 ab, 1890, 1893), Lameere ( 1908, 191 7), Carpenter ( 1951, 1968) and others. In 1968 Carpenter and Richardson mentioned stout lateral spines in the nymph of Mischoptera douglassi on the meso- and metathorax.
The abdominal projections are actually filiforrn, growing in fringe- like rows out of the tergites. However, all previous authors ob- served only the basal parts of several abdominal projections situated laterally, which led to incorrect interpretations. Thus Brongniart ( 1885, p. 63 ; 1885, p. 658; 1890, p. I 540) considered them to be branchio-tracheal appendages, which served for aquatic respiration in nymphs and which were carried over to the adults. In his general account on Carboniferous insects of Commentry, he gave a detailed figure ( 1893, p. 305, p. 298, fig. 50) of an enlarged "lateral lamella" with branched "tracheae" in the genus Corydaloides (Mischopte- ridae). His point of view was followed by Brauer (1886, p. 107), who classified the projections as "persistent abdominal tracheal gills". Handlirsch first ( I 906) stated that Megasecoptera possessed "den- tated lamellar appendages, which were perhaps derived from tracheal gills".
The gill character of the projections was denied by Lameere ( 1908, p. 136; 1917, p. 28; 1917, p. 145), who compared the "lamellae" with the lateral expansions of the Recent mayfly Onisciguster wake- fieldi (N. Zealand). He regarded the projections protruding out from "lamellae" to be backwardly directed spines. Martynov (1938, p. 25) characterized Megasecoptera as having "lateral expansions of abdominal segments with tooth-like or spine- like outgrowths, homologous with prothoracic spines and prothoracic winglets of Palaeodictyoptera, reduced and modified". Carpenter (195 I, p. 353) correctly stated that the projections were extensions of tergites, but also believed them to be short and spine-like in char- acter (Corydaloididae, 195 I, p. 35 I ). A significant step in the research of the character of abdominal projections was the paper on megasecopterous nymphs published by Carpenter and Richardson ( I 968 ) .
In this remarkably preserved
nymph, Mischaptera douglassi, the hind margins of the abdominal tergites, except the last two, bear a row of seven stout "spines". This



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19721 Kukalovii-Peck - Palaeozoic Insect Orders 245 fact was unusual enough to inspire the thoroughfull examination of abdominal tergites of all known Megasecoptera for this feature. After a detailed discussion with Dr. Carpenter (during my tenure as Alexander Agassiz Lecturer in Zoology at Harvard University), I visited the Museum d'Histoire Naturelle in Paris on my return trip to Europe. This institution's collections hold the most extensive material of Paleozoic Megasecoptera (Brongniart, 1893 ; Carpenter, I 95 I ) . I found that each of the sufficiently preserved megasecopteran bodies (mostly Mischopteridae) had prolonged filaments leading from the posterior margin of the abdominal tergites. The projections were visible only under glycerin, a medium which was o~bviously not ap- plied to the fossils by previous students. It should be noted that in the Mischoptera douglassi nymph the bases of the projections give a perfect spine-like appearance, which now seems to be due to incom- plete preservation. Recently, Carpenter and Richardson ( 197 I ) de- scribed long filamentous projections in Eubrodia dabasinskuxi (Brodi- idae) extending posteriorly along the mesothorax to almost the end of the body.
The specimens of Megasecoptera and Palaeodictyoptera newly in- troduced in the present paper contribute significant features to the knowledge of the projections. Sylvohymen sibiricus nsp. (Bardohy- menidae), a megasecopteron from the Lower Permian of Siberia, shows the hollow, broken bases of projections located not only along the posterior margin of abdominal tergites, but also on tergal nota of the whole body (fig. I and pi. I ). M~onsteropterum moravicum nsp., a palaeodictyopteron from the Lower Permian of Czechoslo- vakia, presents well preserved projections (fig. 6 and pi. 3)) showing details of the surface and of multiple branching. Summarizing our present knowledge, we can say that the processes or projections are hollow outgrowths of the tergites and are usually arranged into regular transverse rows, are simple or branched, and are short to very long, according to the particular families. The outgrowths are directed up and backwards from the body, so that they protrude. The ventral side of the ~rojection-bearing bodies is not known. On the thorax, the ~rojections may form spines, or may be filiform, identical to those on the abdomen. The abdominal ~rojec- tions with their superimposed series of fringes, resemble the tradi- tional skirt of the Spanish national female costume. It is possible that all species of Megasecoptera possessed projections, more or less developed, both adults and nymphs. Projections of the same char- acter occurred in some Palaeodictyoptera, but probably not in all families.




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246 Psyche [September
It has taken almost 80 years for acquisition of the above data about these two groups of insects, though they are not rare in Paleozoic deposits. This slow process becomes more understandable after con- sidering the character and nature of preservation of the projections. Protruding above the body in life, they tended to become hidden by the superimposed sediment rather than become compressed at the same level as the body itself during fossilization. The broken and usually more sclerotized bases of the projections are not distinguishable from spines or tubercles and are mostly inconspicuous. Finally, in a ma- trix which does not preserve chitin, the imprints of the projections are vague.
During my study, the projections were thoroughly examined for connections with the insect's body. In the matrix capable of pre- serving chitin (e.g. Cornmentry shale), the projections have the same brown color as the terga. Their surface is covered with a rugosity similar to that on the body (Mazon Creek, Illinois) or with a minor rugosity and scattered sockets of setae (Obora, Moravia). In Mon- steropteruin moravicum, the surface of the projections is identical to that of the legs. The arrangement of the projections is regular and probably characteristic for all genera within a family (I have found this to be true so far for Bardohyrnenidae, Protohymenidae and Mis- chopteridae). The width of the projections varies with the size of specimens; their arrangement is bilaterally symmetrical. The above mentioned features exclude the possibility that the outgrowths are parasitic organisms or fungi.
These projections in the Megasecoptera and Palaeodictyoptera ap- pear unique among insect orders, and their function remains ob- scure. However, several features suggest that they might be homo- logous to certain tergal structures of Odonata. In all Recent Odo- nata, there is a transverse ridge at each end of the tergum, the anterior and posterior transverse carinae (Walker 1953, p. 18). The former is inconspicuous, but the posterior carina is a distinct ridge bearing a row of small tubercles or denticles. By the position and arrangement in rows, the projections in Megasecoptera and Palaeodic- tyoptera are very suggestive of the prolonged and enlarged carinal denticles of Odonata. Their function, of course, presents a com-
plicated problem, which can hardly be solved wi'th fossil material. ORDER MEGASECOPTERA
Family Bardohymenidae Zalessky
Type Genus: Bardohymen Zalessky, 1937.
This family was erected by G. Zalessky ( 1937) and redefined by



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Figure 1. Syloohymen s'tbiricu~ n.sp.; Pr = bases of hollow outgrowth of termites. Holotype: fore wing length 50 mm, width 9.1 mm. Lower Permian of Siberia.



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248 Psyche [September
Carpenter (1947). A significant contribution to the morphology of the wings was published by Carpenter (1962). Until now, the family has been based only upon isolated, more or less fragmentary wings.
The following introduces certain characteristics of body structures and some additional features of wing morphology based upon 5 new specimens from the Lower Permian of Siberia and Czechoslovakia. Wings subequal in length and shape, strongly petiolate, similar in venation; C flattened and wide, very close to Sc; Sc distinguishable as a separate vein only in proximal part of the wing; RI contiguous with C and Sc except in the very distal part of the wing; RI with short terminal branches; Rs originating at about midwing, giving rise to 2-3 branches; M very close to R basally, diverging away from R beyond the first quarter of the wing length; M dividing into MA and MP at variable level, but near to the origin of Rs; MA con- nected with Rs or R with a strong cross vein; 'Cu at the base fused with the stem of M; CuA connected with the stem of M by a strong cross vein; 2 anal veins, A1 long with a pectinate series of branches; A2 very short and simple; cross veins not numerous, usually ar- ranged in 2 rows; veins and wing margin with rows of setal bases or sockets.
Body structures: head small, short and broad, with large pro- jecting eyes ; antennae long, composed of many cylindrical segments ; maxillary palpi robust; prothorax trapezoidal; mesothorax and meta- thorax large in proportion to the rest of the body; legs of middle length, cursorial; abdomen relatively slender tapering abruptly in the anterior part; females with I I visible segments and protruding ovipositor; projections forming rows on the posterior margin of thoracic and abdominal segments; parallel, transverse rows of projec- tions on abdominal terga, and occasionally on thoracic segments ; larger projections located in pairs in the central parts of the body segments. The family Bardohymenidae is closely related by wing morphology to Protohymenidae (Carpenter, 1962)~ which turns out to be true also for the body. However, the wing venation is less advanced, possessing an MA which is not anastornosed with Rs, and a CuA free from M. Also the general form of the wings is less specialized, as the hind wings are almost equal to the fore wings, not reduced in length as in the Protohymenidae. The body in both families is much alike, possessing a large thorax and tapered abdomen. The bardohy- menid body is, in relation to the wings, more heavy. Through the courtesy of Dr. Carpenter I was able to study Protohymen readi Carpenter (1933), Protohymen elongatus Carpenter (1930) and



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19721 Kukalovd-Peck - Palaeozoic Insect Orders 249 Prwtohymen j%m-mianus Tillyard ( I 924) for projections. In all three specimens the bases of projections are present and very similarily dis- tributed as in Bardohymenidae. However, they merge with the un- even surface of
the rock to such an extent that they would be undetectable unless a well preserved specimen, such as the type of S. sibiricus n.sp., were available for comparison. By delicate prepara- tion of the surrounding matrix I was able to1 uncover remnants of projections (P. readi, specimen 3257, Museum of Comp. Zoology, Harvard University; P. permianus, specimen 5053, Peabody Museum, Yale University), which are prolonged and backwardly curved. This fact is very significant, because in Sylvohym-en sibirici~s nsp. (Bardo- hymenidae) the projections continue into the covering matrix and cannot be followed.
The projections in Bardohymenidae and Protohymenidae are ar- ranged in transverse rows. By position and distribution they are very similar to denticles in the transverse carinae of Odonata. In my opinion, these structures may be homologous. Besides, some anisop- teran nymphs (for instance Erpetogomphus designatus, Gomphidae) Needham & Westfall, 1955, bear, on several abdominal terga, paired darker pits, located along the median line precisely like the bases of the large paired projections in Bardohymenidae and Protohymenidae. This similarity is suggestive of ~ossible musculature inside the paired projections in Megasecoptera.
Genera included: Bardohymen G. Zalessky, 1937 (Lower Per- mian, Barda River, U.S.S.R.) ; Sylvohymen Martynov, 1941 (Lower Permian, Tshekarda, Siberia, U.S.S.R. and Lower Permian, Okla- homa) ; Calohynzen Carpenter, 1947 (Lower Permian, Oklahoma) ; Actinohymen Carpenter, 1962 (Lower Permian, Texas) ; Alexahy- men n.g. ( Lower Permian, Czechoslovakia). Genus Sylvohymen Martynov
Sylvohymen Martynov, 1941: 10; Carpenter, 1947: 31; Carpenter, 1962: 37; Rohdendorf, 1962: 68.
Type species: Sylvohymen robustus Martynov, 1938 (OD). This genus is based upon a distal part of a wing from the same locality (Tshekarda) as the presently described specimen of Sibiricus, n.sp., which is much more fully preserved. Carpenter ( 1946, p. 31, fig. 7) described 8. ingens from the Lower Permian of Oklahoma, also based on a distal wing third. The apical parts of the wing in all three specimens resemble each other and the species cannot be separated generically as far as is presently known. Unfortunately, they can also hardly be separated from Bardohymen (this statement



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Psyche [September
PLATE 1
SyIwohyflies. sibwicus n,ap,, obverse. Vie arrows point to the banes of the proJcctioDs on the tergite~. Lower Permian, Siberia. is based MI literature only) and further study of the original mate- rial might find the two genera synonymous. Martyonv's reconstructib of Sylvohymen robustsus ( 194 I ) show- ing MA anastornosing with Rs is obviously incorrect, as the connet- tion of MA with R or Rs by means of a cross vein is characteristic for Bardohymenidae.
Wings long and slender, tapered rather abruptly in the basal third; hind wings slightly longer than fore wings, broader at about mid- wing; Sc recognizable only in proximal half of the wing; Rs with 3 main branches; AI S-shaped; posterior margin in untapered part of wing almost parallel to the anterior margin. Body structures : Prothorax with transverse elevations ; rnetathurax broader than mesothorax; first abdominal segment strongly tapering;



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19721 Kukalovd-Peck - Palaeozoic Insect Orders 25 1 ovipositor in females stout, covered by hairs; projections probably maximally 14 in number in a row.
As shown previously by Martynov ( 1941) and Carpenter ( 1947, p. 32)) Sylvohymen is closely related to the type genus Bardohymen. The reconstruction of Bardohymen magnipennifer (G. Zalessky 1937, p. 603, fig. I) is obviously incorrect for its cubital branches. By the structure of pterostigmal area the genus Sylvohymen is related to Alexahymen n.g., which differs in having a relatively shorter and broader wing with concave posterior margin, small rs a;-ea and AI parallel with posterior margin.
Species included : Sylvohymen robustus Martynov, I 938 (Lower Permian, Oklahoma) ; Sylvohymen sibiricus n.sp. (Lower Permian, Tshekarda, Siberia).
Sylvohymen sibiricus n.sp.l
Figure I, plates I and 2
This species is based upon an obverse and reverse of a female with two complete wings and damaged lateral part of body. The thorax and the abdomen are preserved on the dorsal side, while the head pre- sents a composite of dorsal and ventral surface showing bases of stout palpi. The projections, if only the obverse were known, give the appearance of stout tubercles. In the reverse, however, they con- tinue like hollow tubes into the matrix. For preparing the illustration, both obverse and reverse parts of the specimen were used.
Wings slightly subequal, the hind pair being longer and broader at about midwing; color markings missing; fore wing length 50 mm, maximum width 9. I mm, almost equally broad except for the tapered proximal third; anterior margin slightly convex; C bordering the whole wing; apex bent backward and almost pointed; RI apically diverging to some extent, with 1-3 terminal twigs; Rs with 3 simple long branches; A1 S-shaped with a row of about 9 branches; cross veins about 18 in number; cross vein between RI and Rs forming a heavy bar, thickened at its costal end; hind wing length 51 mm, maximum width 9.7 mm broadest at the mid-wing; hind wing nar- rowing proximally less abruptly; anterior margin somewhat straighter ; RI apically less diverged away from the anterior margin, with only I twig.
'This remarkable specimen was turned over to me for study by the courtesy of Dr. B. B. Rohdendorf, the head of the Paleoentomological De- partment of the Paleontological Institute of the Academy of Sciences in Moscow, for which I express my sincere gratitude.



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Psyche
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PLATE 2
Syiwokymen ~ihiricus n.sp., reverse. The veins are secondarily colored by manganese. Arrows point to hollow continuations of projections into the matrix. Lower Permian, Siberia.




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19721 Kukalovd-Peck - Palaeozoic Insect Orders 253 Body structures: Length of head 1.8 mm, width about 3.6 mm; preserved length of antennae 9 mm, antennae composed of numerous cylindrical segments ; segments of maxillary palpi striated, p reserved segment length 1.1 mm, width 0.8 mm; median line running along the whole body; prothorax length 4 mm, maximum width 8 mm, provided with two obliquely oriented longitudinal elevations and one elevation located anteriorly and centrally; mesothorax length 4.1 mm, probable width 8.8 mm; metathorax length 4.2 mm, maximum width probably 9.2 mm; legs covered by setae; front tibia length 38 mm; hind tibia length about 50 mm; abdomen length 14.5 mm, maximum width 9.4 mm; abdominal segments unequal, length of segments as follows : 1st 2 mm; 2nd 0.8 mm ; 3rd I .3 mm ; 4th I .7 mm ; 5th 2 mm; 6th 2 mm; 7th 0.5 mm; 8th I mm; 9th I mm; 10th 1.6 mm; I ith 0.5 mm; each abdominal segment but the I ith has a transverse flat topped ridge; I ith segment divided by a deep incision into' two lobes; ovipositor stout, reaching much beyond the end of the body, covered by dense stiff hairs oriented anteriorly. Projections: Two stout projections located in the central part of each body segment except the I I th; prothorax with an additional pair of projections anteriorly and with about 8 projections along the pos- terior margin; mesothorax with a row of small projections parallel and near to the anterior margin and with double row of stouter projections on the posterior margin; metathorax with a series of stout projections on posterior margin; abdominal segments with a row of stouter projections on the flat topped ridge and another row of smaller projections bordering the posterior margin; I I th segment
with only the posterior row of minute projections. Holotype : No. I 700/394, Paleoentomological Department, Paleon- tological Institute of the Academy of Sciences in Moscow. Collected in Lower Permian deposits of Tshekarda, Siberia. The preservation of the holotype is very good, particularly be- cause the veins of the wings have been secondarily penetrated and colored by manganese, which enters also the minute transverse cracks. The body is not fully flattened. The abdomen especially is preserved in its original convexity. Some of the bases of the projections are well preserved and only those are introduced in figure I, marked as circles, as they actually appear. The projections were undoubtedly growing out from the tergites in regular rows, but since the surface of the body is uneven, they cannot be distinguished from the irregu- larities of the matrix. The actual length of the projections could not be followed as they continue inside the reverse of the fossil under an acute angle with the body. Their position, however, indicates that



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254 Psyche
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they have been sclerotized. In analogy to the closely related Protohy- menidae, it is probable that the projections were slightly curved and at least several millimeters long.
Genus Alexahymen, new genus
Type species': Alexahymen maruska n.sp., Lower Permian of Moravia. This genus includes one species, represented by 3 incomplete wings. Wings shorter than in the related genus Sylvohymen, broadest be- hind the midwing, tapering gradually towards the base; Sc distinct to about two thirds of the wing length; RI diverging apically slightly from the anterior margin; Rs with two short branches; A1 parallel with the posterior margin; posterior margin slightly concave. Alexahymen differs from other genera of the family Bardohy- menidae in its relatively short and broad, gradually tapering wings, posterior margin concavely shaped, A1
parallel with the posterior
margin and sending off a series of numerous twigs, and small rs area. Species included: Alexahymen maruska n.sp. (Lower Permian, Obora, Moravia) .
Alexahymen maruska n.sp.
Figure 2, 3, 4
Derivatio nominis: In honor of Mrs. Maruska Alexovi, who generously gave support and encouragement to workers at the Obora locality for ten years.
This species is based upon the holotype, represented by a wing without the proximal part, and by two additional, isolated, equally damaged wings. With regard to the close similarity between the fore and hind wings in Bardohymenidae, the position of wings in the pair can be only inferred. However, from analogy with Sylvohymen sibiri- cus, the only bardohymenid with both wings in situ, it seems that the hind wings in this family tended to have a straighter anterior margin and more concave posterior margin. Consequently the hole type (fig. 2) and specimen 2/1972 (fig. 3) are represented probably by the hind wing, while specimen 3/1972 (fig. 4) is more likely the fore wing.
Color markings missing; total wing length about 33-36 mm, maxi- mum width 8.7-9.9 mm; anterior margin slightly convex in the distal part; C bordering the wing; apex more or less pointed; RI with 4-5 very short terminal twigs; Rs branches short; Ax sending off 6- branches; cross veins I 5-16 in number, mostly in double row. Material : Holotype No. I/I 972 (obverse and reverse probably of hind wing) ; specimen No. 2/1972 (obverse and reverse probably of



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Kukalovd-Peck - Palaeozoic Insect Orders 255
Figure 2. Alexahymen maruska n.sp.; hind wing: length 30 mm, width 9 mm. Holotype. Lower Permian of Czechoslovakia. Figure 3. Alexahymen maruska n.sp.; hind wing: length 31.8 mm, width, 9.9 mm. Specimen 2/1972. Lower Permian of Czechoslovakia. Figure 4. Alexahymen maruska n.sp.; fore wing: len,gth 23 mm, width