The earliest Mesopsychidae and revision of the family Mesopanorpodidae (Mecoptera)

Abstract The family Mesopanorpodidae is revised. Most taxa referred to this family are not related to the type genus Mesopanorpodes Tillyard, 1918. The type species of the latter, Mesopanorpodes wianamattensis,is closely related to Mesopsyche Tillyard, 1917. Therefore Mesopanorpodes is transferred to Mesopsychidae Tillyard, 1917 (= Mesopanorpodidae Tillyard, 1918, syn. n.).The earliest Mesopsychidae are described from the Upper Permian of European Russia (Severodvinian; Isady locality, Vologda Province): Permopsyche issadensis gen. etsp. n. (type species) and Permopsyche rasnitsyni sp. n. Two species described under Mesopanorpodes from the Upper Permian of Australia are also included into Permopsyche: Permopsyche belmontensis (Riek, 1953), comb. n., Permopsyche robustus (Riek, 1953) comb. n. The first pre-Triassic Mesopsyche, Mesopsyche incompleta sp. n. is described from the uppermost Permian (the town of Vyazniki, Vladimir Province). Bittacopanorpa javorskii Zalessky, 1935 from the uppermost Permian or basal Triassic of Kuznetsk Basin is identified as a hindwing of Mesopsyche: Mesopsyche javorskii (Zalessky, 1935) comb. n. The origin, evolutionary history, and stratigraphic occurrence of Mesopsychidae are discussed.


Introduction
described Mesopanorpa wianamattensis from the Middle Triassic Ashfield Formation of the Wianamatta Group in New South Wales as an aberrant Mecop-  Novokshonov, modified after Novokshonov (1997c). Not to scale. equately preserved specimens and contain inaccurate drawings and fantastic venational interpretations, in which obvious artifacts are interpreted as characters of specific or even generic rank and hindwings are often misinterpreted as forewings. Thus, these taxa should be considered as of unknown systematic position until revised in detail.
The Jurassic genera Itaphlebia Sukatcheva, 1985 andChrysopanorpa Ren, 1995 were originally placed in Mesopanorpodidae as well. Novokshonov (1997a, b) synonymized these two genera and transferred them to Nannochoristidae. Itaphlebia appears to be the most common and widespread nannochoristid during the Jurassic. Its diagnosis, composition, and distribution, as well as the overall composition of the Mesozoic Nannochoristidae have been discussed recently by Liu et al. (2010). Hong (2007) referred Itaphlebia again to Mesopanorpodidae and described I. tongchuanensis from the Tongchuan Formation of Shaanxi. However, this species is not related to Itaphlebia, being instead rather similar to Mesopsyche, where it apparently belongs.
Stylopanorpodes eurypterus, Netropanorpodes decorosus, and N. sentosus Sun, Ren & Shih, 2007(Sun et al. 2007b) from the mid-Jurassic Jiulongshan Formation of Inner Mongolia, China, originally placed in Mesopanorpodidae, are venationally similar to the species of Itaphlebia occurring in the same deposits (Sun et al. 2007c, Liu et al. 2010) and belong to Nannochoristidae as well. Novokshonov et al., 2004 from the basal Triassic of Northern Russia has been transferred to the related family Nedubroviidae (Bashkuev 2011). Therefore, with the above-mentioned taxa discarded, Mesopanorpodidae remain composed of only three species of Mesopanorpodes from the Upper Permian and Middle Triassic of Australia. But are they actually congeneric?

Mesopanorpodes mostovskii
Re-examination of available photographs of M. wianamattensis reveals that its CuA is distinctly bent distal to the origin of MP, and the base of CuA is shifted distad and inclined backwards, like in Mesopsyche (Fig. 1A-B). Thus, Mesopanorpodes appears venationally indistinguishable from Mesopsyche. Here I provisionally retain Mesopanorpodes as a separate genus until the complete revision of Mesopsyche. Unlike M. wianamattensis and Mesopsyche, both species described by Riek have the base of CuA short and transverse, with the intercubital space not expanded, which is presumed to be a plesiomorphic condition. These species are included here in the new genus Permopsyche gen. n.
In this paper, two new species of Permopsyche, P. issadensis sp. n. (type species) and P. rasnitsyni sp. n., are described from the Upper Permian of European Russia. These are the oldest currently known records of Mesopsychidae. The new material includes a number of well-preserved fore-and hindwings, which allow establishing yet another difference between Permopsyche and Mesopsyche, the position of the hindwing CuA vein with respect to the membrane. In P. issadensis CuA is concave (while the R 1 is convex), as is typical of Permochoristidae, while in Mesopsyche spp., including the Permian species, as well as the other Mesozoic mesopsychid genera, both CuA and R 1 are convex, like in most post-Paleozoic Mecoptera.
The earliest record of Mesopsyche, and the only one known so far to be definitely pre-Triassic, Mesopsyche incompleta sp. n., is described from the uppermost Permian of the European Russia.
Bittacopanorpa javorskii Zalessky, 1936 from the transitional Permian-Triassic sequence of the Kuznetsk Basin (Babiy Kamen' locality, Maltsevo Formation), known only from a wing base ( Fig. 8G-H), originally placed in Neorthophlebiidae and tentatively transferred to Permotipulidae (Bechly and Schweigert 2000), can be identified as a hindwing with venation almost identical to that of the above-mentioned Mesopsyche incompleta sp. n. (Fig. 8B).

Material and methods
The study is based on examination of ca. 60 fossil specimens from the collection of Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow (PIN). The holotype of Bittacopanorpa javorskii Zalessky is preserved in the collection of the Central Research Geological Prospecting Museum, Saint Petersburg (CRGPM).
Fifty-three isolated wings of Permopsyche were collected from a lens of fluvio-lacustrine deposits within the Sukhona River section, in Vologda Province, north-central Russia (Isady locality). It corresponds to the Kalikino Member of the Poldarsa Formation, and is dated the latest Severodvinian (correlated with the Lower Wuchiapingian: Golubev in press).
Five specimens of Mesopsyche were collected from the Balymotikha locality, an outcrop of lacustrine deposits of Vyazniki Permian-Triassic sequence, at the town of Vyazniki, Vladimir Province, central Russia. It is dated the latest Vyatkian (Late Changhsingian), somewhat below the Permian-Triassic boundary (Newell et al. 2010).
The fossils were examined with a Leica M165C stereomicroscope and photographed using an attached Leica DFC 425 digital camera. Images were digitally processed with Helicon Focus v. 5.1 and Adobe Photoshop CS3 graphic software. Line drawings were made using Inkscape v. 0.48 vector graphics editor.
On the line drawings the wings are oriented with their apices to the right, while some photographs are reversed left-right for better comparison.

Remarks. The genus
Mesopanorpodes is restricted here to its type species, M. wianamattensis. Though Mesopanorpodes appears venationally indistinguishable from Mesopsyche, it doesn't seem appropriate to synonymize these genera prior to the complete revision of the latter. The genus Mesopsyche (sensu Novokshonov 1997c, Novokshonov andSukacheva 2001) includes apparently quite diverse insects and is quite loosely defined and likely heterogeneous, so its further dividing into several genera cannot be excluded.
Etymology. From the Permian and Greek psyche, "soul" or "mind," the word often used for devising names of delicately winged insects. Gender feminine.
Diagnosis. In forewing, SC long, bearing only inclined fore branch, connecting distally with R 1 by crossvein. Costal space narrow. Both RS and MA forks not longer than their stems. MP 4-branched. CuA base oblique to transverse, not distinctly in-clined backwards; M 5 present or lost. Anal area not expanded. Crossveins not numerous. In hindwing, CuP concave with respect to membrane (in contrast to convex R 1 ).
Comparison. Differs from the closest genus Mesopsyche by the base of CuA being oblique to transverse (not inclined backwards), costal space narrower, and hindwing CuP concave with respect to membrane.
Composition. In addition to the type species, from the same locality, P. rasnitsyni sp. n.; and from the Upper Permian of Australia, P. belmontensis (Riek, 1953) comb. n. and P. robustus (Riek, 1953) comb. n. Remarks.
The assumption that one of the key characters, the position of hindwing CuP with respect to the membrane, known in the type species only, is shared by the other species is tentative and requires further verification.
Diagnosis. Differs from P. belmontensis by wing shape, with anterior margin straight and posterior apical margin tending to oblique, different crossveins arrangement, and strongly unsclerotized MP stem. Differs from P. robustus by branch of SC located more basally and A 3 simple. Additionally differs from both species by considerably smaller size.
Description. Forewing. Moderately broad (length/width ratio 2.3-2.9:1); anterior margin nearly straight, slightly convex basally; apex obtuse to rounded. SC long, reaching or almost reaching basal margin of pterostigma; SC branch approximately at middle of RS+MA stem (somewhat variable in paratypes). Pterostigma distinct, widened, with oblique basal margin. R 1 simple, gently bending posteriad at pterostigma. RS and MA forks equally short, approximately as long as their stems. Nodal line distinct, arched, running from tip of SC to hind margin at apex of CuA. Thyridium present as unsclerotized section on MP stem spanning from approximately 1/3-1/2 of its length down to fork, accompanied by desclerotized spot at point of branching of RS and MA ("thyridulum", the term introduced by A.P. Rasnitsyn in Ren et al. 2009). Connection between CuA and MP variable ( Fig. 4; see also Remarks), from joined at one point (X-junction), with CuA base oblique and M 5 lost, to forming well-developed cubitomedian Y-vein with almost equal arms at obtuse angle, with CuA base transverse and M 5 quite long. cua-cup crossvein transverse. Three simple anal veins. Crossveins not nu- merous, mainly distinct or slightly weakened, forming rather stable pattern: one long, oblique, sigmoidally curved r 1 -rs crossvein; four crossveins between RS, MA, and MP branches; mp-cua and cua-cup crossveins of standard position; cup-a 1 and a 1 -a 2 located stepwise along with the base of CuA; occasionally, a 2 -a 3 present. Wing membrane darkened in distal wing half, restricted by nodal line, with saturated patch at center of wing.
Hindwing. Both venation scheme and coloration similar to those in forewing, adjusted for general difference between fore-and hindwings typical of Mecoptera. SC short, reaching wing midlength, variably forking apically (Fig. 6). Pterostigma distinct. R 1 with inclined branch in pterostigmal area. A 1 separating from CuP relatively closely to base.
Remarks and discussion. In P. issadensis the wing size varies conspicuously. As shown in the size distribution diagram for forewings ( Fig. 5; Table 1), the presence of Y-vein and the transverse (rather than oblique) shape of CuA base (hollow squares vs filled squares) both correlate with the increased wing size (irrespectively of the length/ width ratio). However, the size distributions of the two morphotypes overlap broadly. The two wing morphotypes may represent sexual dimorphism. Alternatively, they can be attributed to slight differences in flight mechanics depending on the body size. The distinctive and uniform wing color pattern makes it unlikely that the morphotypes represent two closely related species.
The nodal line (the line of wing flexion) in the forewing of the new species is essentially similar to that of both Mesopsyche (Novokshonov 1997c) and the recent Panorpa (Ennos and Wooton 1989), suggesting a similarity between flight mechanics of Mesopsychidae and Panorpidae.  Hindwings of Permopsyche are almost as abundant at Isady as the forewings. All the hindwings examined, as far as their preservation allows to tell, have the set of characters (including coloration) diagnostic of the forewings of P. issadensis and can be confidently referred to the same species.  Table 1; see text for explanation. Diagnosis. Similar to P. issadensis in general venation scheme, but of larger size, with MA fork shortened, intercubital space widened, and wing membrane almost uncolored.
Description. Forewing length/width ratio about 2.8-3:1; anterior margin nearly straight; apex obtuse to rounded. Costal space very narrow along its entire length. MA fork distinctly shorter than RS fork. MP unsclerotized for more than 1/2 of its length. CuA base long, nearly transverse, M 5 present or lost. Intercubital space rather expanded. Wing membrane mostly uncolored, with small diffuse dark patch at center of wing.
The wing is 6 mm long, 2.1 mm wide, subtriangular, with anal area narrowed and posterior apical margin slightly oblique; MA forking before RS. The wing is entirely uncolored (neither part, nor counterpart showing any trace of coloration). The specimen may either be an aberrant specimen of Permopsyche issadensis, or represent a different species, but describing a separate species based on a single wing does not seem well justified.
Comparison. Differs from Permopsyche by the base of CuA being inclined backwards, costal space widened, and hindwing CuP convex.
Description. Forewing. Anterior margin slightly convex. Costal space somewhat wider than subcostal one. Pterostigma distinct, lanceolate. SC not reaching the pterostigma, bearing one oblique distal branch; connected distally with R 1 by short transverse crossvein. R 1 sharply curved posteriad at origin of weak distal branch in pterostig-  mal area. RS forking somewhat before than MA. Thyridium at MP stem before fork. CuA base obscure, presumably curved backwards and located somewhat distal to M 5 . Crossvein cua-cup slightly sigmoid, distinctly curved backwards. Crossvein pattern typical of genus. Color pattern in form of sparse dark spots, mostly around crossveins.
Hindwing venation and coloration similar to those in forewing. SC slightly shortened, reaching level of RS+MA bifurcation, somewhat beyond wing midlength, forking apically. Pterostigma distinct. R1 nearly straight, turning apically towards anterior margin. R 1 branch obscure. CuA distinctly convex along the whole length.
Comparison. The new species substantially differs from others by SC with a single, distally located fore branch.

Discussion
The systematic position of Mesopsychidae and the entire "suborder" Paratrichoptera was discussed by Novokshonov and Sukatcheva (2001). Recent studies of complete mesopsychid fossils from the Middle Jurassic and Lower Cretaceous of China revealed the long siphonate mouthparts indicating fluid feeding on reproductive organs of gymnosperm plants (Ren et al. 2009. Mesopsychidae, together with mid-Mesozoic Aneuretopsychidae, Pseudopolycentropodidae, and now the Late Permian to Early Triassic Nedubroviidae (Bashkuev 2011), form a distinct long-proboscid clade within Mecoptera, the Aneuretopsychina.
The finds described herein reveal main trends in the evolution of Mesopsychidae after their separation from the permochoristid-like ancestor. These are: -Change in the forewing CuA base inclination and position: from proximal and inclined forwards (typical of Permochoristidae) to inclined backwards, and probably also shifted distad. -Change in position of the hindwing CuA: from concave (Permopsyche) to convex (most Mesopsychidae). -Loss of fusion of CuP and A 1 veins in the hindwing: from quite basally fused in Permopsyche, through a rudimentary basal fusion in Mesopsyche (as indicated by Novokshonov (1997c) in M. shcherbakovi), to becoming secondary free along their whole length in the mid-Jurassic and early Cretaceous genera. -Increase in the average wing size, from 5-6 mm in the Late Permian to 20-30 mm since the Late Triassic.
The Permian Mesopsychidae occurred together with Nedubroviidae (in Isady, Balymotikha, and probably Belmont; Bashkuev 2011), which already have typical long siphonate mouthparts, and the possession of those in early mesopsychids (and even in the ancestral permochoristid lineage) can be assumed as well.
New finds also cast light on the stratigraphic distribution of the Aneuretopsychina scorpionflies, which appear to be the most common group of Mecoptera during the latest Permian -early Middle Triassic time interval (viz. Mesopsychidae, Nedubroviidae, and later also Pseudopolycentropodidae). They initially replaced Permochoristidae in the end of Permian, and were in turn progressively supplanted during the Triassic -Early Jurassic by Parachoristidae and Orthophlebiidae, which gave rise to the modern mecopteran lineages. In the mid-Jurassic -Lower Cretaceous insect assemblages, Aneuretopsychina scorpionflies are rather rarely found, constituting only a minor component of the mecopteran faunas.