Mongolbittacus daohugouensis, Petrulevicius & Huang & Ren, 2007

Petrulevicius, Julián F., Huang, Di-Ying & Ren, Dong, 2007, A new hangingfly (Insecta: Mecoptera: Bittacidae) from the Middle Jurassic of Inner Mongolia, China, African Invertebrates 48 (1), pp. 145-152 : 149-151

Mongolbittacus daohugouensis sp. n. Figs 1–4 Etymology: After type locality.

Description:

Body. Abdomen 6.5 mm long, with 7 visible segments, last segment rounded with cerci; hind and mid (?) femur about 4.1 mm long, hind tibia 4.5 mm long, mid (?) tibia 4.3 mm long, hind tarsus about 5.3 mm long, mid tarsus 6.5 mm long; two long tibial spurs on all 4 legs; tarsomere 3 of midtarsus (?) with several long hairs along ventral plane ( Fig. 3C ); tarsomere 4 of hind tarsus enlarged and with several strong, small ventral spines ( Fig. 3D ); tarsomere 5 of hind tarsus with less strong, small ventral spines; pretarsal claws not preserved.

Wings. Fore wing (basal part missing): preserved length 11.1 mm; maximum width 3.2 mm; basal part of wing narrow; ScP reaching wing margin just basal to RP fork; ScP without crossveins to RA; R continuous with RA; RA simple and slightly spoonlike, reaching antero-apical wing margin; crossvein between RA and RP1+2; sigmoidal crossvein between RP1+2 and RP3+4; crossvein between RP2 and RP3+4; crossvein between RP3+4 and MA; RP arising from R at an acute angle; RP1+2 arising at almost a right angle from RP, sub-symmetrical with RP3+4+MA; RP1 and RP2 bifurcating symmetrically; RP1+2 forking just basal to curved part of RA; MA nearly straight though fractured by anterior part of the Kreuz; RP3+4+MA + RP3+4 sigmoidal; RP3+4 arising from RP3+4+MA at an acute angle, bent posteriorly after crossvein to RP1+2, and running more or less parallel to MA; separation of RP3+4 basal to bifurcation of MP1+2; Kreuz not aligned; posterior part of Kreuz reaching MP3 just distal from its base; two crossveins between MA and MP1; one crossvein between MP1 and MP2; one crossvein between MP2 and MP3; MP4 fused with CuA1+2 and closely aligned with MP3; one crossvein between MP3 and MP4+CuA1+2; CuA arising from Cu at an oblique angle and fused with MP for a short distance; CuA3+4 and CuP running parallel to each other; final part of CuP strongly curved and reaching wing margin at approximately right angles; AA3+4 reaching wing margin slightly distal to bifurcation of R; one crossvein between CuP and AA3+4; AA3+4 strongly curved posteriorly and linked to AP1+2 by short crossvein; in left wing, curvature of AA3+4 is more pronounced and crossvein longer than in right wing, where AA3+4 is less curved ( Figs 3A, 3B ); AP1+2 running well separated from wing margin and reaching wing margin just basal to CuA, producing a wide posterior anal field; AP1+2 reaching wing margin with a strong curvature after crossvein to AA3+4, the curvature fractured in the left wing and rounded in the right ( Figs 3A, 3B ).

Hind wing (basal part missing): preserved length 9.5 mm; maximum width 2.7 mm; ScP reaching wing margin basal to forking of RP; ScP without crossveins to RA, shorter than in forewing; R continuous with RA; RA simple and slightly spoon-like (?), reaching antero-apical wing margin; crossvein between RA and RP1+2; oblique crossvein between RP3+4 and base of bifurcation of RP1 and RP2; RP arising from R at approximately right angles; RP1+2 arising from RP at an acute angle, sub-symmetrical with RP3+4 + MA; RP1 and RP2 bifurcating sub-symmetrically; MA nearly straight, fractured by anterior part of the Kreuz; RP3+4+MA + RP3+4 sigmoidal; RP3+4 arising from RP3+4+MA at an acute angle, bent posteriorly after crossvein to RP1+2, and running more or less parallel to MA; separation of RP3+4 basal to bifurcation of MP1+2; Kreuz not aligned; posterior part of Kreuz reaching MP3 just distal from its base (?); a single crossvein between MA and MP1 and between MP1 and MP2; MP4 fused with CuA1+2 and closely aligned with MP3; CuA3+4 and CuP running parallel to each other; final part of CuP strongly curved, reaching wing margin at a right angle.

Holotype: NIGPAS 133709, almost complete and articulated female specimen, without head; thorax not well preserved in lateral view, mid and hind legs legs preserved. CHINA: Inner Mongolia: Ningcheng County, Daohugou; Middle Jurassic , Jiulongshan Formation.

Remarks: Bittacidae are usually preserved disarticulated and are thus represented by isolated wings in the fossil record. The entomofauna from the Middle Jurassic of Daohugou is mainly represented by complete specimens.This introduces the possibility of observing intraspecimen variation in the wing venation. This variation was observed in M. daohugouensis in the venation of the anal field ( Figs 3A, 3B ). Variation of the wing venation in different specimens of the same recent species has been studied by different authors and summarised by Willmann (1989), who also provided new data. This variation is not documented in fossil specimens of the family, and the existence of such variation at about 170 Ma is of great interest. We have to take into account the review comment of Dr J.G.H. Londt, stating that the specimen appears to be quite small for a bittacid and that small individuals may possess ‘simplified’ morphology—maybe even reduced venation. As this particular specimen is unique, being the only specimen of this species available for study, we are unable to estimate the variation in size between individuals of this species. Thus it is a possibility that the intraspecimen variation of wing venation in M. daohugouensis gen. et sp. n. is due to its small size. Future discoveries and subsequent studies of new specimens may help to resolve this matter.

ACKNOWLEDGMENTS

We extend our gratitude to M.M. Solórzano Kraemer (Institut für Paläontologie, Universität Bonn, Germany) for assistance with German translation and M.C. Digiani (Museo de La Plata, Argentina) for valuable help and discussion. We also thank J.G.H. Londt (Natal Museum, South Africa) and an anonymous reviewer for improvement of the manuscript.

We thank for the funds and support provided for this research: DR, grants Nos 30370184 and 30430100 from the National Natural Science Foundation of China, Scientific Research Key Program (KZ200410028013) and PHR Project of Beijing Municipal Commission of Education; DYH, grant No. 40672013 from the National Natural Science Foundation of China and the Major Basic Research Project (2006- CB806400) from MST of China; JFP, grant PIP 6393 from CONICET (National Research Council, Argentina), DAAD (German Academic Exchange Service) and MNHN (National Museum of Natural History, France), also grants directed by P. Wilf and provided by USA institutions: National Science Foundation (grant DEB-0345750) and National Geographic Society (grant 7337-02).

Figures

Fig. 1. Mongolbittacus daohugouensis gen. et sp. n., holotype. Scale bar = 2 mm.

Fig. 2. M. daohugouensis holotype, camera lucida drawing. Scale bar = 2 mm.

Fig. 3. M. daohugouensis holotype: (A) anal field of right fore wing; (B) anal field of left fore wing; (C) fore or middle last two tarsomeres; (D) hind last two tarsomeres. Scale bars = 0.2 mm.

Fig. 4. M. daohugouensis holotype, camera lucida drawing of right fore wing. Scale bar = 2 mm.