Ptychopteridae, Osten Sacken, 1862

Lukashevich, Elena Dmitrievna & Ansorge, Jörg, 2024, First Upper Triassic Diptera (Insecta) from Germany, Zootaxa 5403 (1), pp. 115-129 : 119-121

Family Ptychopteridae incertae sedis

( Fig. 4 )

Material. SNHMB-G.5996 , part and counterpart of an incomplete wing, without posterior part.

Locality and horizon. Fuchsberg near Seinstedt, Lower Saxony, Germany; ’Fossilführende Wechselfolge’ alternating fine grained sand, silt and clay, Shipingia gerbachmanni conchostracan zone; latest Sevatian (uppermost Norian); Upper Triassic.

Description. Isolated fragmentary wing about 6 mm long. Wing transparent, with pterostigma, without dark spots. Wing venation: Sc ending well beyond wing midlength, level with furcation of R 4+5; Rs origin at about 0.17 wing length; Rs stem slightly curved; R 2+3 equidistant from R 1 and R 4; R 2+3 2.1x as long as R 3; veins R 1 beyond R 2, R 3, R 4 and probably R 5 subparallel; R 4+5 fork 2.5 x as long as R 4+5 stem; r-m close and distal to Rs furcation, dividing R 4+5 stem as 1:7; M stem somewhat desclerotized; M forking in proximal wing half; basal portion of M 3+4 (before m-cu) twice longer than m-cu.

Remarks. At the first glance due to wing incompleteness, it looks like a member of Limoniidae with similar division of radial sector into R 2+3 and R 4+5 and R 2 as crossvein such as Triassic Mabylesia Shcherbakov, 1995, Archilimonia Krzemiński & Krzemińska, 2003 and Metarchilimonia Blagoderov & Grimaldi, 2007 ( Shcherbakov et al. 1995; Krzemiński & Krzemińska 2003; Blagoderov et al. 2007). The characters of wing venation uniting these three genera (Rs divided into R 2+3 and R 4+5, extremely short R 4+5, and M forking in the wing midlength) are symplesiomorphic features, which are very rare in extant taxa of Tipuloidea ( Lukashevich & Ribeiro 2019). However, two of these three peculiarities (short R 4+5 stem and M forking in the wing midlength) are absent in the German wing. Moreover, in contrast to SNHMB-G.5996, in these limoniid genera Sc and Rs are much shorter (Sc ending about wing midlength; Rs origin at 0.34–0.38x wing length), r-m never closed to Rs furcation and m-cu is positioned much more distal, just before or at fork M 3+ 4 in distal half of the wing. Described position of r-m and m-cu, longer Rs and R 4+5 stem as well as M forking clearly before the wing midlength are characters of Mesozoic Ptychopteridae , so this wing is considered a member of the family.

This wing fragment obviously is non congeneric with Crivoptychoptera gen. nov. however, the exact systematic generic position is unclear due to incomplete state of preservation: medial veins are diagnostic in the Ptychopteridae but almost absent in the fragment and even their number (four or three) is unknown as well as position of crossvein im. It is not a member of Eoptychopterininae because Rs and R 4+5 are not sharply bent. The immaculate wings with vein R 2 + 3 equidistant from R 1 and R 4 are known in monotypic Proptychopterininae. However, it hardly can be a member of the genus, because in Proptychopterina Kalugina, 1985 r-m is about midlength of R 4+5 and level or even distal to M 3+4 furcation, but in the Triassic wing r-m is closed to Rs furcation whereas M 3+4 fork is not preserved. Moreover, up to now Proptychopterina is unknown in European deposits ( Lin & Lukashevich 2006). Such position of r-m, close to Rs fork, is typical for several genera of Eoptychopterinae , usually of Jurassic deposits of Europe (including Eoptychoptera from Liassic deposits of Germany; Ansorge, 1996) and such affinity seems to be most probable. However, vein R 2 + 3 is close to R 1 in Eoptychopterinae ( Lukashevich et al. 1998), so the subfamiliar position remains unclear due to incomplete preservation of the wing.

Figures

FIGURE 4. Wing of Ptychopteridae inc. sed., SNHMB-G.5996, Fuchsberg, Tr 3. Line drawing and photo, total view. Scale bar = 1 mm.