Hercostomus deltodontus, 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 : 554-556

Hercostomus deltodontus sp. nov.

( Figs 2, 3 , 13–15 )

Diagnosis. First flagellomere blunt and rounded apically. Basal segment 0.25 times as long as apical portion of arista ( Fig. 13 ). Cercus nearly flabellate ( Fig. 15 ). Phallus elongated, with 1 large and sharp dorsal tooth ( Fig. 14 ).

Description. Male ( Fig. 2 ). Body length 2.5 mm, wing length 3.0 mm. Head dark metallic green, with pale pollinosity; face gradually narrowed downward. Hairs and bristles on head black, postocular bristles black, posteroventral hairs yellowish brown. Antenna black ( Fig. 13 ); first flagellomere blunt and rounded apically, 1.3 times longer than wide, with short pale pubescence; arista subapical, shorter than head width, black, almost bare, basal segment 0.25 times as long as apical portion of arista. Proboscis yellowish brown, with brown to pale hairs and 2 black bristles at base; palpus dark brown, with pale hairs, and with 2 brown bristles at tip. Thorax metallic green, with pale pollinosity. Hairs and bristles on thorax black; 6 dc, acr absent. Scutellum with 2 pairs of long strong sc. Legs wholly black except by brownish trochanters and bases of tibiae brownish. Hairs and bristles on legs black. Fore coxa anteriorly with rows of irregular hairs, mid coxa anteriorly with rows of irregular hairs at base, hind coxa with 1 outer bristle at middle. Mid tibia with 2 pd, 1 av; with 2 apical bristles. Hind tibia thickened towards tip, basal portion lighter than that of fore and mid tibiae, with 2 ad, 1 pd, 2 av; with 2 apical bristles. Hind tarsomere 1 with 1 av at base; with 1 short apical bristle. Relative lengths of tibia and 5 tarsomeres of legs LI: 3.2: 1.5: 0.7: 0.6: 0.4: 0.5; LII: 4.0: 2.0: 1.0: 1.0: 0.5: 0.6; LIII: 4.7: 1.6: 1.5: 1.0: 0.7: 0.6. Wing nearly hyaline, tinged brown; veins brown, R4+5 and M1+2 slightly convergent apically. CuAx ratio 0.5. Squama yellowish with 7 black hairs. Halter pale. Abdomen metallic green, with pale pollinosity. Hairs on abdomen pale, bristles on abdomen black. Fifth and sixth sternites with strong bristles. Male genitalia ( Figs 14, 15 ): Epandrium distinctly longer than wide, with 1 thin digitation; inner epandrial lobe small, with 1 short thin bristle at tip, outer epandrial lobe long, thickened at tip, apically with 3 strong bristles. Surstylus long, nearly triangular, sharp at tip, slightly bent, with 2 bristles near base. Cercus nearly flabellate, with several long digitations, with black bristles and brownish hairs. Hypandrium with 1 inner tooth. Phallus elongated, distinctly longer than epandrium, with 1 big sharp dorsal tooth. Female ( Fig. 3 ). Body length 3.0 mm, wing length 3.0 mm. Very similar to male, but first flagellomere nearly as long as wide, abdominal sternites 5–6 with black hairs instead of bristles.

Type material. HOLOTYPE, ♂ labeled: China: Tibet, Zhangmuzhen, Deqingtang (N28°00'10.4" E8°58'52.9"), 3062 m, collected from path in woodland on mountain, 2013. VII.26, Xiaoyan Liu ( CAU). PARATYPES: 1 ♂ 1 ♀, same data as holotype.

Distribution. Oriental: China (Tibet).

Remarks. The new species is somewhat similar to H. xizangensis Yang from Tibet of China, but may be separated from the latter by the large, sharp dorsal tooth on the phallus and short inner epandrial lobe of the epandrium. In H. xizangensis , the phallus is somewhat folded near the apex, the inner epandrial lobe of the epandrium is quite long, nearly as long as the outer epandrial lobe ( Yang 1996a).

Etymology. The specific name refers to the large sharp dorsal tooth on the phallus.

Figures

FIGURES 2 – 3. Hercostomus deltodontus sp. nov. 2. Male; 3. Female. Scale bar = 1.0 mm.

FIGURES 13 – 15. Hercostomus deltodontus sp. nov., male. 13. Antenna, scale bar = 0.2 mm; 14. Genitalia, lateral view, scale bar = 0.5 mm; 15. Male cercus, scale bar = 0.5 mm. Abbreviations: epn = epandrium, hyp = hypandrium, ph = phallus, sur = surstylus, lat = epandrial lobe, pos = postgonite.