The oldest Calosargus Mostovski, 1997 from the Middle Jurassic of China (Diptera: Brachycera: Archisargidae) Author Zhang, Kuiyan Author Yang, Ding Author Shih, Dong Ren Chungkun text Zootaxa 2007 1645 1 17 journal article 10.5281/zenodo.179727 de333d52-b2e2-47cb-b3de-5c313a86ad12 1175-5326 179727 Calosargus ( Calosargus ) bellus Zhang, Yang & Ren , sp. nov. ( Figs. 1–6 ) Diagnosis. Vei n R s 1 about twice as long as vein Rs2; vein R2+3 arising slightly distal of base of cell d; vein R2+3 ending at vein R1 near wing margin; crossvein r-m located at about basal 2/5 of cell d. Etymology. The specific name refers to the Latins bellus (pretty). Holotype . CNU-DB-NN2007004, an almost complete male with both wings in dorsal view. Paratype . Part and counterpart CNU-DB-NN2007005, CNU-DB-NN2007006, an almost complete adult body with both wings in lateral view. Type locality and horizon. Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia , China ; Jiulongshan Formation, the Middle Jurassic (Aalenian-Bajocian). FIGURES 1–2. Calosargus ( Calosargus ) bellus sp. nov. Holotype, photograph. (1) Body with wings in dorsal view; (2) apex of abdomen. FIGURES 3–4. Calosargus ( Calosargus ) bellus sp. nov. Holotype, camera lucida drawing, based on the original photograph, in dorsal view. (3) right wing; (4) apex of abdomen. Description. Body length 17.3 – 17.6 mm ; wing length 9.4 – 10.3 mm , wing width 2.8 – 2.9 mm . Head round, slightly narrower than thorax. Eyes large, bare, dichoptic; ommatidia visible clearly. Thorax black. Legs pubescent. Fore and mid tibiae slender; hind tibia with 1 spur, femur long, robust; first tarsomere distinctly longer than following tarsomeres. Wing hyaline: Crossvein h sometimes slant. Vein C ending at wing tip; veins C, Sc and R1 markedly thick; vein Sc long, extending far beyond middle of wing. Ve in R 1 long and robust; vein Rs1 arising from middle of wing, about twice as long as vein Rs2; vein R2+3 arising slightly distal of base of cell d; vein R2+3 ending at vein R1 near wing margin; veins R4 and R5 short; vein R5 ending far beyond apex of wing, relative lengths of veins Rs3, R4 and R5 about 6: 3: 4. Crossvein r-m located at basal 2/5 of cell d. Vein M3 absent, vein CuA1 arising from cell d. Vein CuP present. Cell sc wide open, mouth of cell sc about 3 times as wide as that of cell r4, mouth of cell r1 narrow, mouth of cell r4 about twice as wide as that of cell r1. Cell br nearly as large as cell bm. Cell d short and wide; base of cell m1 about 1/3 – 1/5 as wide as that of cell m2; mouth of cell m1 nearly as wide as that of cell m2. Mouth of cua1 wide open, about 7 times as wide as that of cell cup. Halter well-developed. Abdomen slender, narrowing toward tip, covered with setulae. Eight segments visible. Segment I evidently short. Segments I and II with wide black stripe at middle. Segments II to VII with distinct stria at side. FIGURE 5. Calosargus ( Calosargus ) bellus sp. nov. Paratype. Body with wings photograph in lateral view. Remarks. C. ( C. ) bellus sp. nov. looks like C. ( C. ) tatianae Mostovski, 1997 very much in the following aspects: vein Rs1 long, about twice as long as vein Rs2; vein R2+3 arising slightly distal of base of cell d; cell d wide, crossvein r-m located at basal 2/5 of cell d; mouth of cell m1 slightly wider than that of cell m2. However, it can be easily separated from the latter by vein R2+3 long, ending at vein R1 near wing margin, and base of cell m1 about 1/3 – 1/5 as wide as that of cell m2. In tatianae , vein R2+3 is short, ending at vein R1 far before wing margin; the base of cell m1 is about 1/2 as wide as that of cell m2.