Hercostomus nuciformis, 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 : 560-561

Hercostomus nuciformis sp. nov.

( Figs 7, 8 , 20, 21 )

Diagnosis. First flagellomere pointed at tip, 2.1 times longer than wide. Basal segment of arista 0.6 times as long as apical portion of arista ( Fig. 20 ). Cercus nearly triangular, digitations at tip each separate slightly wider. Phallus thin, hazelnut-shaped at tip ( Fig. 21 ).

Description. Male ( Fig. 7 ). Body length 2.5 mm, wing length 3.0 mm. Head dark metallic green, with pale gray pollinosity; face gradually narrowed downward. Hairs and bristles on head black, postocular bristles black, posteroventral hairs black. Antenna ( Fig. 20 ) wholly black; first flagellomere nearly triangular, blunt at tip, 2.1 times longer than wide, with brownish pubescence; arista subapical, slightly longer than width of head, black, almost bare, basal segment 0.6 times as long as apical portion of arista. Proboscis dark yellow, with yellowish hairs and 1 weak black bristle at tip; palpus dark brown, with 2 black bristles at tip. Thorax dark metallic green, with pale gray pollinosity. Hairs and bristles on thorax black; 6 dc, 7 pairs of regular acr. Scutellum with 1 pair of sc. Legs mainly yellow, but mid and hind femora blackish on dorsum, tarsi brown to black toward tip. Hairs and bristles on legs black. Fore coxa anteriorly with rows of bristles. Mid and hind coxae each with 1 outer bristle. Fore tibia with 3 ad. Mid tibia with 2 ad, 3 pd, 1 pv and 4 apical bristles. Hind tibia with 3 ad, 1 pd and 2 apical bristles. Relative length of tibia and 5 tarsomeres of legs LI: 2.1: 1.0: 0.5: 0.4: 0.3: 0.4; LII: 3.2: 1.0: 0.7: 0.7: 0.5: 0.6; LIII: 3.5: 1.0: 1.3: 0.9: 0.6: 0.7. Wing nearly hyaline, tinged brown; veins brown, R4+5 and M1+2 slightly convergent apically. CuAx ratio 0.6. Squama pale yellow with 8 black hairs. Halter pale yellow. Abdomen dark metallic green, with thick pale gray pollinosity. Bristles black, hairs pale. Male genitalia ( Fig. 21 ): Large, nearly half as long as abdomen. Epandrium distinctly longer than wide; inner epandrial lobe flat and broad, with incision at middle, outer epandrial lobe somewhat triangular at apex, with 3 long bristles at tip. Inner surstylus with wavy margin, with 1 short bristle at middle, outer surstylus pointed at tip. Subepandrial process pointed at tip, with 2 bristles near base. Cercus nearly triangular, with several digitations, with black hairs and bristles. Hypandrium with 1 weak inner tooth. Phallus thin, hazelnut-shaped at tip. Female ( Fig. 8 ). Body length 2.6 mm, wing length 3.2 mm. Very similar to male, but first flagellomere 1.6 times longer than wide.

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: 4 ♂ 1 ♀, same data as holotype.

Distribution. Oriental: China (Tibet).

Remarks. The new species is somewhat similar to H. dentalis (Yang) from Tibet of China, but may be separated from the latter by the blunt tip of the first flagellomere and hazelnut-shaped tip of phallus. In H. dentalis , the first flagellomere is pointed at tip, the phallus is truncate at tip ( Yang 1997b).

Etymology. The specific name refers to the hazelnut-shaped tip of the phallus.

Figures

FIGURE 7 – 8. Hercostomus nuciformis sp. nov. 7. Male; 8. Female. Scale bar = 1.0 mm.

FIGURES 20 – 21. Hercostomus nuciformis sp. nov., male. 20. Antenna, scale bar = 0.2 mm; 21. Genitalia, lateral view, scale bar = 0.3 mm. Abbreviations: epn = epandrium, hyp = hypandrium, ph = phallus, sur = surstylus, lat = epandrial lobe, pos = postgonite, cer = cercus.