Corresponding author: Junfeng Zhang ( firstname.lastname@example.org )
Academic editor: Sonja Wedmann
© 2017 Junfeng Zhang.
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Citation: Zhang J (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): 61-67. https://doi.org/10.3897/dez.64.11724
A new species of Sinonemestrius Hong & Wang, 1990 is described and illustrated based on a complete compression fossil of the fly. Currently placed in Rhagionemestriidae or Xylophagidae, the present study concludes that the morphology of the new find indicates that Sinonemestrius is a heterostomid genus within Tabanomorpha. The placement of Ahirmoneura neimengguensis K-y Zhang et al., 2008 is reassessed. It demonstrates close similarities in body structure and wing venation to those of Sinonemestrius, and can be provisionally transferred from Nemestrinidae to Heterostomidae: Sinonemestriinae.
Diptera, Tabanomorpha, Sinonemestrius new species, Cretaceous, Laiyang Formation, China
The Jehol biota (sensu lato) constitutes a suite of fossil plants and animals that lived during the Early Cretaceous in eastern- and north-eastern Asia (
A rare and unusual nemestrinid-like brachyceran wing from the Laiyang Formation in the vicinity of Tuanwang Village, Laiyang, Shandong, China was described by
Material. The holotype of a shale fossil compression of a male sinonemestriid fly described herein is deposited in the collections of the Nanjing Institute of Geology and Palaeontology (
Illustrations. Specimen descriptions, photomicrographs and line drawings were done with the application of glycerol to the surface of the specimens. The line drawings were produced with the aid of a camera lucida and the digital photomicrographs were taken using a stereomicroscope (Leica M205C).
Wing venation terminology here follows
Colour described here refers to that of the fossil, where patterning is preserved, not the hue of the live fly.
Sinonemestrius tuanwangensis Hong & Wang, 1990
Sinonemestrius akirai Jarzembowski & Mostovski, 2000 and Sinonemestrius completus sp. n., besides the type species Sinonemestrius tuanwangensis Hong & Wang, 1990.
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.
The original generic diagnosis was defined based on wing impressions (
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,
Similar to Sinonemestrius tuanwangensis, but R2+3 smoothly curved downwards and parallel to R1, ending at C instead of R1 end; fork of R4+5 distinctly distad to fork of M1+2; crossvein r-m meeting anterior margin of discal cell basad to its midlength; wing membrane with few markings (only limited to “Pt” and below it).
Male medium-sized flies. Female unknown. Head moderately large, semiglobose, slightly narrower, but distinctly shorter, than thorax; vertex plus frons more or less flattened; eyes large, holoptic, covering almost entire head; antenna shorter than head, scape subquadrate, slightly wider than long, pedicel much shorter, less than one half of scape length, more than twice wider than long, first flagellomere extremely swollen, nearly pyriform, much longer and wider than scape and pedicel combined, less than twice as long as wide, other flagellomeres gradually tapering apically, about three times as long as first flagellomere (Figs
Thorax subovate, mesoscutum longer than wide, slightly wider than head; scutellum small, rounded apically, distinctly wider than long; wing nearly three times as long as wide; C thickened but thinned just at wing tip; R1 slightly curved smoothly, about three-fourths of wing length; Rs arising from R more or less late, about at one-third of wing length; R2+3 parallel to R1, ending at C; “Pt” well developed, another brown marking between R1 and R2+3 below base of “Pt” present (Figs
Abdomen ovate-oblong, with seven segments visible, clearly longer than head and thorax combined, with first segment longest, second segment widest, slightly wider than thorax; male genitalia longer than sixth segment with gonostylus (?) darkish brown, very narrow, strongly curved inwards.
Holotype: length of body 10.9 mm; head, 1.4 mm; thorax, 3.6 mm; abdomen 6.4 mm. Length of wing 7.4 mm, width of wing 2.9 mm.
Sinonemestrius completus sp. n. differs from the type species Sinonemestrius tuanwangensis by the following features: R2+3 slightly curved, parallel to R1 and not meeting R1 end apically, fork of R4+5 distinctly distad to level of fork of M1+2, crossvein r-m meeting anterior margin of d cell basad to its midlength and wing membrane with a few markings (only limited to “Pt” and below it). On the other hand, this new species differs from Sinonemestrius akirai by Rs arising from R stem late (at about one-third of wing length vs near to wing base), the slightly curved R2+3 which runs parallel to R1 (vs R1 and R2+3 clearly convergent apically), fork of R4+5 distad (vs basad) to level of fork of M1+2 and cell m3 open (vs closed before hind margin of wing). Unfortunately, the body structures cannot be compared because the descriptions of the two known species are based on wing impressions.
Latin, completus (complete), referring to the species erected based on a complete fly.
Type locality and horizon: Laiyang Formation, in the vicinity of Tuanwang, Laiyang, Shandong, China (Lower Cretaceous).
The Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.
Sinonemestrius completus sp. n., no.
Sinonemestrius completus sp. n., no.
Difference and similarity between four sets of wings. Line drawings of holotypes. A Sinonemestrius completus sp. n., B Sinonemestrius tuanwangensis Hong & Wang, 1990 (after
On the basis of a single wing of a fly from the Lower Cretaceous of the Laiyang Formation, Shandong, China,
The body structures and wing venation of Sinonemestrius completus sp. n. reveal that Sinonemestrius is very similar to the modern genus Heterostomus. This is based on the following synapomorphies: hemispherical head comprised mostly of the eyes; male holoptic; antennal flagellum with eight flagellomeres, stylus (or arista) absent; a pair of metatibial spurs present (although very small in Sinonemestrius completus sp. n.). In addition, there are close similarities in wing venation: wing membrane always with markings; C reaching wing tip, thinned behind wing tip; R2+3 ending close to R1 end; R4 sigmoidal; R5 aligned with stem of R4+5; R5 (or M1) ending at wing tip; crossvein r-m present; cell br very narrow, distinctly narrower than cell bm; discal cell usually narrow and long; cell m3 open (only closed in Sinonemestrius akirai); cell cu (traditionally anal cell) narrow and long (narrowly open in Sinonemestrius, closed in Heterostomus). For this reason, the proposal is supported here that Sinonemestrius could be related to heterostomid flies (
I am deeply indebted to Dr M. B. Mostovski (The Steinhardt Museum of Natural History and Israel National Center for Biodiversity Studies, Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel and School of Life Sciences, University of KwaZulu-Natal, Scottsville, South Africa) and Dr A. Nel (Muséum National d’Histoire Naturelle, Entomologie, Paris, France) for critical remarks and improving the previous version of the manuscript. I also sincerely thank Visiting Prof. Dr E. A. Jarzembowski (NIGPAS and The Natural History Museum, London, UK) for suggesting edits to the English. The research was supported by the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (Y421120502).