Sinonemestrius Hong & Wang, 1990

Zhang, Junfeng, 2017, On the enigmatic Sinonemestrius Hong & Wang, 1990, with description of a new species based on a complete fossil fly (Diptera, Brachycera, Tabanomorpha, Heterostomidae), Deutsche Entomologische Zeitschrift 64 (1), pp. 61-67 : 61

Sinonemestrius Hong & Wang, 1990

Type–species.

Sinonemestrius tuanwangensis Hong & Wang, 1990

Included species.

Sinonemestrius akirai Jarzembowski & Mostovski, 2000 and Sinonemestrius completus sp. n., besides the type species Sinonemestrius tuanwangensis Hong & Wang, 1990.

Diagnosis.

Medium-sized flies with robust build; body covered with dense hairs but devoid of setae; head moderately large, semiglobose, shorter and narrower than thorax, comprised mostly of the eyes; eyes holoptic in male, hind margin with emargination; antenna short, corneous, with eight-segmented flagellum, first flagellomere swollen, stylus (or arista) absent; wing membrane with markings; R1 relatively short; R2+3 curved, relatively short, ending at, or near to, R1 tip; R4 usually sigmoidal; R5 nearly straight, aligned with stem of R4+5; crossvein r-m present; R5 or M1 ending at wing tip; M2 ending behind wing tip; cell cu (traditionally anal cell) open; metatibia with two very short spurs; empodium present.

Remarks.

The original generic diagnosis was defined based on wing impressions ( Hong and Wang 1990, Jarzembowski and Mostovski 2000). A revised and supplemented diagnosis including some critical structures of the body is proposed here based on a complete compression fossil of the fly.

Based on a single impression fossil of a nemestrinid-like fly from the Jurassic of the Daohugou biota in the vicinity of Daohugou Village, Wuhua Township, Ningcheng County, Inner Mongolia, China, K-y Zhang et al. (2008) erected a new genus Ahirmoneura (type species: Ahirmoneura neimengguensis K-y Zhang et al., 2008). They classified this genus in Nemestrinidae . It certainly resembles representatives of the extinct nemestrinid subfamily Archinemestriinae and even some living tangle-veined flies in that R4, R5, M1 and M2 end near to the wing tip. Nevertheless, the clearly short R1 and the absence of the so-called diagonal vein exclude this genus from the Nemestrinidae . In many features (including body structures and wing venation), Ahirmoneura resembles Sinonemestrius (lack of setae on the body; hemispherical head; elongate-ovate abdomen covered with hairs; very short R1; R4, R5, M1 and M2 ending near to wing tip; and the so-called diagonal vein absent). It should be noted that the wing venation of Ahirmoneura neimengguensis demonstrates very close similarities to that of Sinonemestrius akirai (Figs 3C, D). The former species differs from the latter one only by the longer, straight R2+3, which ends at C far apart from the end of R1, M2 (instead of M1) ends just at the wing tip and r-m meets the anterior margin of the discal cell near to its base. Unfortunately, the crucial structure of the antenna of Ahirmoneura neimengguensis is unknown. Until a new find (including antenna) of this species is available, Ahirmoneura can only be provisionally assigned to Heterostomidae : Sinonemestriinae.