Cothornobata nigrigenu ( Enderlein, 1922 )

Li, Xuankun, Marshall, Stephen A. & Yang, Ding, 2015, A review of the Oriental species of Cothornobata Czerny (Diptera, Micropezidae, Eurybatinae), Zootaxa 4006 (2), pp. 201-246 : 235

15. Cothornobata nigrigenu ( Enderlein, 1922)

( Figs. 19 , 20 )

Grammicomyia nigrigenu Enderlein, 1922: 173 . Type locality: Burma, Toungoo, Karenni, 3000 ft. Trepidarioides nigrigenu (Enderlein) : Hennig, 1935: 307.

Cothornobata nigrigenu (Enderlein) : McAlpine, 1975: 239.

Cothornobata nigrigenu (Enderlein) : Steyskal, 1977: 13.

Diagnosis. Arms of genital fork convergent on distal 1/3, widest point across arms almost twice as wide as base at midpoint, basal tubercle absent, medial tubercle strong. Pregonite forming a microsetulose, broad, crescent-like lobe; postgonite twisted, corkscrew-like.

Description. Male. Body length 10.0–11.0 mm, wing length 7.0–8.0 mm.

Head mostly subshiny blackish with very thin gray pollinosity. Frontal vitta blackish-brown with dark yellow apex, densely microsetulose, about 2/3 width of frons; lower orbital plate dull pollinose; ocellar triangle black; median occipital sclerite with a small dark yellow spot at middle; lunule dark yellow; face pale yellow, densely microsetulose; gena yellow, lightly pollinose; clypeus uniformly blackish, shiny. Setae and setulae on head black; postgena with 1 strong seta at lower margin.

Antenna brownish-yellow; first flagellomere 1.6X as long as broad; pedicel with 1 ventral apical seta nearly length of first flagellomere; arista nearly 3.6X length of first flagellomere, brownish-yellow, long pubescent on basal half. Proboscis brownish-yellow with brown apex, setulae brown. Palpus yellow, setulae black.

Thorax black, with pale gray pollinosity. Scutellum flat, directed posteriorly. Setae on thorax black, setulae blackish; katepisternum with 3 strong setae.

Legs mostly yellow, except hind coxa brown, fore femur blackish on apical 1/2, mid and hind femora with blackish-brown apex; fore tibia blackish, mid and hind tibiae yellow to brown with darker base and apex; tarsi blackish-brown, except mid basitarsus dark yellow with brown tip.

Wing light brown; distal band brown, basal to middle of distal section of M1; discal band light than distal band, along M1 and reached to R4+5, basal to middle of penultimate section of M1. Bm-cu in line with CuA2, A1+CuA2 3.1X as long as CuA2; distance between apex of R2+3 and R4+5 0.6X as long as M1 beyond dm-cu ( Fig. 19 C). Halter pale yellow with brown base.

Abdomen mostly brownish-yellow with pale gray pollinosity, tergites 2–6 pale yellow with pale gray pollinosity apically. Pleuron pale gray. Epandrium brownish-yellow. Genital fork brown to dark brown, with blackish-brown to black setulae; arms strongly divergent basally and convergent on distal 1/3, widest point across arms almost twice as wide as base at midpoint; basal tubercle absent, medial tubercle strong, broadly convex ( Fig. 19 D). Distiphallus inflated apically, glans absent. Pregonite long and slender, crescent-like. Postgonite slender and twisted, corkscrew-like ( Fig. 19 GH).

Female. Body length 11.0 mm, wing length 8.5 mm. Tergites 1–5 pruinose, dull; tergite 6 and oviscape blackish-brown, shiny, bare except for sparse setulae.

Type material: HOLOTYPE: BURMA, Toungoo, Krennl, 3000’, 1914.iv, “gesammelt von Micholitz” (♀, MNBG) (Examined and photographed by the second author in 2002). In addition to the data label it has a red “ Type ” label and a label reading “ Grammicomyia nigrigenu ” ♀, det. Enderlein 1921). PARATYPE: SIKIIM, von Burnham (1 ♂, MNBG) (Examined and photographed by the second author in 2002).

Other material examined. CHINA, Yunnan Province: Honghe, Lvchun, Huanglian Mountain, 1790 m, 17.v.2009, Xiushuai Yang (1 ♂, CAU); Honghe, Lvchun, Huanglian Mountain, Yakou, 12.v.2012, Ding Yang (1 ♂, CAU); Dehong, Yingjiang Nabang, 3.v.2012, Feiyang Liang (1 ♂, CAU). INDIA, Meghalaya: Nongph Forest, 22- 28.iv.1980, Amnon Freidberg (7 ♂, USNM); Assam: 10min Tinsukia, in jungle, 1924. iii.29, D.E. Hardy (2 ♂ 1 ♀, USNM).

Distribution. Oriental: Burma, China (Yunnan), India, Laos, Sikkim, Thailand, Vietnam.

Remarks. Cothornobata nigrigenu is recorded from China for the first time. This species differs markedly from congeners by its corkscrew-like postgonite.

Specimens from India and China differ in some details (length of genital fork bristles, shape of inside surface of genital fork), suggesting that more than one species might be involved. The structure of the unusual twisted postgonite is consistent across specimens from all parts of this species range, however, suggesting that this is a single widely distributed species. We thus interpret the above noted small differneces as infraspecific variation.

Figures

FIGURE 19. Cothornobata nigrigenu Enderlein, male. A, left lateral; B, head; C, wing; D, genital fork; E, genitalia, left lateral; F, genitalia, posterior; G, aedeagus and associated structures, left lateral; H, aedeagus and associated structures, ventral. Scale bars = 1 mm.

FIGURE 20. Cothornobata nigrigenu Enderlein. A, TYPE, female, left lateral. B, USNM specimen, male, left lateral.