Bashkonia, Lukashevich, 2021

Lukashevich, Elena D., 2021, The oldest Diptera (Insecta) from the Upper Buntsandstein (early Middle Triassic of Europe, Zootaxa 5067 (1), pp. 135-143 : 137

Bashkonia gen. nov.

( Figure 1 )

Type species Bashkonia franconica sp. nov.

Etymology. The generic epithet refers to Alexey Bashkuev, a recognized collector and expert on Triassic insects. The name is feminine.

Diagnosis. Wings elongate, pterostigma large. Crossvein sc-r far from Rs origin. R kink long and shallow, opposed to long M+CuA fusion; arculus inclined; R 2+3 fork short and wide; Rs relatively long, more than 2/3 wing length; R 4+5 fork long, 10 times longer than R 4+5 stem; R 5 convexity continued along Rs up to MA, forming false vein fv between R and M sectors; r-m jointing R 5 base and basal 1/3 of M 1+2 stem. M forking before Rs bifurcation, near wing midlength; M 1+2 and M 3+4 forks rather long and subequal; im connecting M 1+2 stem and M 3; M 1+2 forking far beyond im; M 3+4 forking clearly distal to R 4+5 furcation; d cell subequal to M 3+4 fork; m-cu in distal wing half, near midlength of d cell, ending on straight M 3+4. CuA bent at m-cu; CuA apex closer to R 1 apex than to Sc apex; CuP entering margin near wing midlength, strongly diverging from CuA in its distal 1/4, CuP being weak after its divergence with cubital fold icu. Two cubital folds well developed: curved one behind entire length of CuA and straight one icu before CuP to CuA apex. A 1 distal to cu-a long.

Species included. Monobasic.

Comparison. The new genus differs from both other genera of Nadipteridae , Nadiptera Lukashevich, 1995 and Tanus Krzemiński & Krzemińska, 2003 in sc-r position (closer to Rs origin than to Sc apex in Nadiptera and Tanus ), shorter Rs and in CuA, which is longer (instead of apex, closer to level of Sc apex than to R 1 apex) and bent at mcu. The new genus shares with Nadiptera false vein fv between R and M sectors and CuP strongly diverging from CuA ( Fig. 2A ), whereas it shares with Tanus M furcation and CuP apex in midlength of the wing and r-m proximal to m-cu ( Fig. 3 ).

Remarks. Characters typical of the family are observed in the wing venation of the new genus: Sc apex beyond wing midlength, distal to Rs bifurcation, the crossvein sc-r not terminal; R distinctly kinked in horizontal plane, Rs forking symmetrically before Sc apex, free R 2 reaching wing margin, R 4+5 fork several times longer than short R 4+5 stem; long convex M base aligned with CuA, M stem forking symmetrically, d cell narrow and long with m-cu ending on straight М 3+4; A 1 not reaching margin, A 2 forming anal loop, anal lobe somewhat produced.

The cubital fold icu reaching CuA apex, found in the new genus, is also present in other Triassic Diptera , the tipulomorph Vladiptera Shcherbakov, 1995 ( Vladipteridae ; Fig. 2B ) and the psychodomorph Tillyardiptera Lukashevich & Shcherbakov, 1999 (Tillyardipteridae) , but they were missed in the original descriptions ( Shcherbakov et al. 1995: fig. 24; Lukashevich & Shcherbakov 1999: fig.1). Such cubital fold is not a common character of Diptera but it is well known in extant and extinct Ptychopteridae as well as false vein fv between R and M sectors and A 1 retaining distal to cu- a as a rather long spur (e.g. Lukashevich 2012).

Figures

FIGURE 1. Bashkonia franconica gen. et sp. nov., holotype SMTE 6123/1-61 (Lengfurt, Germany, Tr2): A, B. Positive and negative impression of isolated wing. C. Line drawing of wing. Scale bars equal 1mm.

FIGURE 2. SEM images (uncoated, BSE) of Diptera wings:A. Nadiptera anachrona Lukashevich, 1995 (Nadipteridae), holo- type PIN No. 371/926,?male, left wing (Sogyuty, Kyrgyzstan, J 1). B. Vladiptera kovalevi Shcherbakov, 1995 (Vladipteridae), holotype PIN No. 2497/305, isolated wing (Kendyrlik, Kazakhstan, Tr 3). Scale bars equal 1mm.

FIGURE 3. Photos of Tanus triassicus Krzemiński & Krzemińska, 2003 (Nadipteridae), holotype No. 5336, male: A. Total view. B, C. Left and right wings (Vosges, France, Tr2). Arrows mark crossvein m-cu. Scale bars equal 1mm.