Trihennigma, Lara & Lukashevich, 2013

Lara, María Belén & Lukashevich, Elena D., 2013, The first Triassic dipteran (Insecta) from South America, with review of Hennigmatidae, Zootaxa 3710 (1), pp. 81-92 : 84-89

Trihennigma gen. nov.

Type species. Trihennigma zavattierii sp. nov.

Differential diagnosis. Wing rather broad, with vestigial pterostigma and without spots at crossveins; long strong Sc ending just before R 2+3 bifurcation and possibly distal to M 1+2 bifurcation; postsectoral sc-r probably nearly level with R 5 origin; supernumerary crossveins r-rs, r3-r4, r4-r5 and r5-m1; R 2 longer than R 2+3, R 4 almost as long as half of wing, entering margin at wing tip; im not preserved, m-cu just before M 3+4 fork; M 4 curved backwards before apex; CuA section before m-cu twice as long as section beyond it; anal loop broad, subequal to 1A beyond it, the latter terminating at deep alular incision, anal lobe possibly produced.

Species included. Monobasic.

Etymology. From the Triassic period and the genus name Hennigma .

Remarks. Combination of long R 2+3 fork, curved M 4 and broad anal loop has been known within the family only in the monobasic superfamily Kuperwoodiinae . The new genus resembles Metatrichopteridium and Daohennigma in the long Sc and extremely short M stem (the correspondingly long d cell is hypothesized), and the positions of R 4 (ending at wing tip) and m-cu (just before M 3+4 bifurcation). Such strong Sc, as well as 1A terminating at a deep alular incision, has been recorded in both species of Metatrichopteridium (basiala is not seen on the single specimen of Daohennigma ); a similar set of supernumerary crossveins is known in Daohennigma . The wing under description is distinguishable from Daohennigma by the more distal position of unaligned r3-r4 and r4-r5, and the absence of spots on crossveins; in fact, these may be species-level differences.

We agree with Ansorge (2001) that the subcostal veinlets mentioned in the original description of Hennigma are artifacts of preservation and are absent in the holotype of M. cladistorum , as well as in other hennigmatids ( Figs 1 , 5 , 6 ). However, his redrawing of the wing base is incorrect ( Ansorge 2001: Fig. 3c ): cu-a is certainly preserved as it was shown in Shcherbakov et al. (1995: Fig. 33) and can be seen in Trihennigma gen. nov.; moreover, in both genera, 2A is not marginal and a small alula is visible in M. cladistorum and is likely to be present in the new genus ( Figs 5 , 6 ).

Figures

FIGURE 1. Wing venation of Hennigmatidae (holotypes): A, Kuperwoodia benefica Lukashevich, 1995; B, Anemeca liya Shcherbakov, 1995; С, Metatrichopteridium cladistorum (Shcherbakov, 1995); D, Daohennigma panops Lukashevich et al., 2006; modified after Shcherbakov et al., 1995 (A–C) and Lukashevich et al., 2006 (D).

FIGURE 3. A, Metatrichopteridium cladistorum (Shcherbakov, 1995): holotype PIN 3965/2789; B, Daohennigma panops Lukashevich et al., 2006: holotype NIGPAS 133706.

FIGURE 5. Basiala of Hennigmatinae: A, B, Trihennigma zavattierii gen. et sp. nov.: holotype MCNAM-PI 24607, part and inverted counterpart; C, Metatrichopteridium cladistorum (Shcherbakov, 1995): holotype PIN 3965/2789. Abbreviation: ai— alular incision.

FIGURE 6. Proximal part of the wing of Metatrichopteridium cladistorum (Shcherbakov, 1995): holotype PIN 3965/2789: A, drawing; B, SEM image (SE). Abbreviation: ai—alular incision.