Zhiganka Lukashevich 1995
Creators: name: Lukashevich, Elena D.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Ptychopteridae
Zhiganka

description: Genus: Zhiganka Lukashevich, 1995
(Figures 1–4, 5A, 6 A–D)
Type species. Zhiganka comitans Lukashevich, 1995: 170, fig. 1e,g.
Diagnosis (emended). Adult. Medium-size gracile flies, 9–13 mm long (Fig. 1B, G). Head not appressed to thorax (Figs 2A, D, 3A). Antenna with 19 flagellomeres, each with distinct scattered (4?) macrosetae and short pubescence, apical flagellomere reduced to button-like structure (Figs 2A, C, 3B). Clypeus acutely triangular, labrum small, sclerotized, labella large. Maxillary palpus elongate, with apical and preapical segments subequal (Figs 1A, 2D, 3A). Antepronotum well developed, prescutal suture distinct, scutum with incomplete transverse suture, all pleural sclerites without setae, transepimeral suture present (Figs 2D, 3A, 4F). Wings rather broad, slightly shorter than abdomen, with macrotrichia confined to apex adjacent to costa; C ending at wing apex, Rs stem long, aligned with straight R 4+5 stem, fork R 4+5 longer than R 4+5 stem; crossvein r-m under Rs furcation; spurious vein between veins R and M long; M forks before r-m; M 1+2 unforked, straight, and extremely thin; CuA slightly sigmoidal beyond m-cu; anal lobe well developed (Figs 1B, G, 2B, G, 3C, 4 A–C, 5A, 6A–C). Legs uniformly dark, without banding, tibial spur formula 1:2:2, foreleg spur spine-like, unmodified (Fig. 1 C–F). Abdomen narrow in both sexes (Fig. 1B, G). Male: epandrium divided into epandrial lobes, surstyli distinct. Gonocoxite without secondary lobe. Gonostylus simple lobe-like, pubescent. Hypandrium divided into basal and terminal divisions (Figs 2E, F, 3 F–H, 4D, E). Female: cerci tablike, setose, lightly sclerotized (Fig. 1H). Spermathecae absent or unsclerotized.
Species included. Besides the type species from Zhigansk (Batylykh Formation, Yakutia, Russia; Lower Cretaceous), Z. woolgari Lukashevich, Coram, Jarzembowski, 2001 from Clockhouse (Wealden Group, United Kingdom; Upper Hauterivian) and Z. longialata sp. nov. described below from Khasurty (Gusinoe Ozero Group, Transbaikalia, Russia; Lower Cretaceous).
Remarks. The genus was established based on isolated wings and pupal fragments (the only immature stage known so far). For adults of each previously known species only an incompletly preserved isolated wing was described, so the diagnosis was limited to wing venation. The additional crossvein r-m was cautiously shown with a dotted line in Z. comitans (Lukashevich, 1995: fig. 1g) but was not observed in Z. woolgari (Lukashevich et al., 2001: fig.10). Reexamination of the holotype of Z. comitans by SEM (Fig. 5B) made it clear that this additional r-m is a preservation artifact, the vein M 1+2 is the thinnest and a long spurious vein (a longitudinal vein-like thickening in the membrane between veins R and M, bisecting crossvein r-m and ending in cell r 5) is present. Therefore, the venation patterns of the type species and the new species described herein (Fig. 5A) are identical. The holotype of Z. woolgari was not available for the study. Macrotrichia on the apical part of the wing are conspicuous in the new species (Figs 2G, 6B, C), but are barely discernible, without certainty, in the type species; however, this can be due to a poor state of preservation of Z. comitans. The new species is, therefore, included in Zhiganka and the diagnosis of the genus is revised accordingly.
description: Published as part of Lukashevich, Elena D., 2019, Review of the fossil record of Bittacomorphinae (Diptera: Ptychopteridae), pp. 566-578 in Zootaxa 4661 (3) on pages 567-568, DOI: 10.11646/zootaxa.4661.3.9, http://zenodo.org/record/3380981