Hercostomus bisetus, Tang, Chufei, Zhang, Lili & Yang, Ding, 2014

Tang, Chufei, Zhang, Lili & Yang, Ding, 2014, New species of Hercostomus baishanzuensis group from Tibet (Diptera: Dolichopodidae, Dolichopodinae), Zootaxa 3881 (6), pp. 549-562 : 552-553

Hercostomus bisetus sp. nov.

( Figs 1, 11, 12 )

Diagnosis. First flagellomere brownish and blunt at tip. Basal segment of arista 0.3 times as long as apical portion of arista ( Fig. 11 ). Abdominal sternite 5 with 2 long bristles at tip on posterior margin medially. Outer epandrial lobe of epandrium long, thin and straight. Cercus nearly square, with extremely long bristles. Phallus thickened and bent ( Fig. 12 ).

Description. Male ( Fig. 1). Body length 3.3 mm, wing length 3.8 mm. Head dark metallic green, with pale gray pollinosity; face gradually narrowed downward. Antenna mostly black, first flagellomere brownish at tip; first flagellomere blunt at tip, 1.3 times longer than wide, with brown pubescence; arista subapical, shorter than head width, black, almost bare, basal segment 0.3 times as long as apical portion of arista. Proboscis brown, with 1 bristle at base; palpus small, brown, with yellowish hairs and 2 short black bristles at tip. Thorax metallic green, with pale gray pollinosity. Hairs and bristles on thorax black; 5 dc, acr absent. Scutellum with 2 pairs of long strong sc. Legs mainly black, but trochanters, bases of femora and tibiae yellow. Hairs and bristles on legs black. Fore and mid coxae anteriorly with rows of irregular bristles. Hind coxa with 2 rows of irregular hairs on outer portion; apically with 1 bristle. Fore femur with 1 pv near apex. Mid femur with 1 av near apex. Fore tibia with 1 ad, 2 pd, 7 pv; with 3 apical bristles. Mid tibia with 3 ad, 2 pd, 1 av; with 3 apical bristles. Hind tibia with 4 ad, 3 pd, 1 av; with 2 apical bristles. Relative lengths of tibia and 5 tarsomeres of legs LI: 1.6: 0.8: 0.4: 0.3: 0.2: 0.2; LII: 2.2: 1.0: 1.2: 0.8: 0.6: 0.5; LIII: 2.5: 1.0: 0.7: 0.6: 0.4: 0.3. Wing nearly hyaline, tinged brown; veins brown, R4+5 and M1+2 slightly convergent apically. CuAx ratio 0.5. Squama yellowish. Halter pale. Abdomen metallic green, with pale gray pollinosity. Hairs and bristles on abdomen black. Only abdominal sternite 5 with 2 long bristles at tip. Male genitalia ( Fig. 12 ): Epandrium slightly longer than wide; inner epandrial lobe small, outer epandrial lobe long, thin and straight, with 1 long bristle at middle and 2 bristles at tip. Surstylus bifurcated, inner arm with 1 process at middle, outer arm thickened at base, bifurcated, both arms long and thin. Cercus nearly square, with several digitations, and with extremely long bristles. Hypandrium with 1 inner tooth. Phallus thickened at middle, bent, edentate. Female. Unknown.

Type material. HOLOTYPE, ♂ labeled: China: Tibet, Zhangmuzhen, Deqingtang (N28°00'10.4" E85°58'52.9"), 3062 m, collected from path in woodland on mountain, 2013. VII.26, Xiaoyan Liu ( CAU). PARATYPES: 2 ♂, same data as holotype ( CAU).

Distribution. Oriental: China (Tibet).

Remarks. The new species is somewhat similar to H. curviphallus (Yang et Saigusa) from Shaanxi and Yunnan of China, but may be separated from the latter by the edentate phallus and the square cercus with the extremely long bristles. In H. curviphallus , the phallus has two teeth and the bristles on the cercus are relatively short ( Yang & Saigusa 2002).

Etymology. The specific name refers to the two long bristles of abdominal sternite 5.

Figures

FIGURES 11 – 12. Hercostomus bisetus sp. nov., male. 11. Antenna, scale bar = 0.2 mm; 12. Genitalia, lateral view, scale bar = 0.3 mm. Abbreviations: epn = epandrium, hyp = hypandrium, ph = phallus, sur = surstylus, lat = lateral lobe, pos = postgonite, cer = cercus, ceb = cercal bridge.