Hercostomus triangulatus sp. nov.

Figs 8, 12-14

Diagnosis.

Antenna mainly dark yellow; postpedicel blackish with basal ventral surface dark yellow, 1.2 times longer than wide, obtuse at tip; arista black, basal segment 0.25 times as long as apical segment. All coxae dark yellow. Male cercus nearly triangular with weak denticles and 3 relatively long finger-like processes.

Description.

Male (Fig. 8). Body length 3.7-4.1 mm, wing length 3.3-3.6 mm.

Head metallic green with dense pale grey pollinosity. Hairs and bristles on head black, middle and lower postocular bristles and posteroventral hairs yellow. Antenna (Fig. 12) dark yellow except scape blackish at base and postpedicel blackish with base and ventral surface dark yellow; postpedicel 1.2 times longer than wide, somewhat acute at tip; arista blackish with short pubescence, basal segment 0.25 times as long as apical segment. Proboscis brownish yellow with black hairs; palpus brownish, with dark yellow hairs and 1 dark yellow apical bristle.

Thorax metallic green with pale grey pollinosity. Hairs and bristles on thorax black; 6~8 irregularly biseriate acr short hair-like; 6 long strong dc. Scutellum with 2 pairs of sc, basal pair short hair-like. Propleuron with yellowish hairs and 1 black bristle on lower portion.

Legs yellow; all coxae yellow; all tarsi brown to dark brown from tip of tarsomere 1 onwards. Hairs and bristles on legs black; mid and hind coxae each with 1 outer bristle; mid and hind femora each with 1 preapical bristle; fore tibia with 1 ad, 2 pd and 2 short apical bristles; mid tibia with 4 ad, 2 short pd, 1 av and 4 short apical bristles; hind tibia with 3 ad, 3 pd, 4 short av (2 inner bristles thin, 2 outer bristles thick) and 3 apical bristles. Hind tarsomere 1 with 1 short ventral bristle at base. Relative lengths of tibia and 5 tarsomeres of legs LI: 2.0: 1.1: 0.5: 0.4: 0.3: 0.2; LII: 2.8: 1.5: 0.8: 0.7: 0.4: 0.3; LIII: 3.4: 1.0: 1.2: 0.5:?:?. Wing nearly hyaline, veins dark brown; R4+5 and M distinctly convergent apically; CuAx 0.5. Squama yellow with dark yellowish hairs. Halter yellow.

Abdomen metallic green with pale grey pollinosity. Hairs and bristles on abdomen black; tergite 1 with several short yellow hairs; sternites 2-3 with short yellow hairs. Male genitalia (Fig. 14): Epandrium distinctly longer than wide, narrowed at tip; epandrial lateral lobe relatively short and thick. Subepandrial process (Fig. 13) with two processes separated, narrowed at tip. Male cercus nearly triangular with some weak denticles and 3 relatively long finger-like processes bearing long bristles on apical margin. Hypandrium somewhat acute at tip.

Female. Body length 3.0-3.6 mm, wing length 3.6-3.7 mm.

Type material examined.

Holotype: male, China, Inner Mongolia, Tongliao, Daqinggou, 180m, 2014.VII.24, Ning Wang & Ding Yang (CAU). Paratypes: 3 males 1 female, same data as holotype (CAU); 8 males 3 females, China, Inner Mongolia, Tongliao, Daqinggou, 180 m, 2014.VII.23, Ning Wang & Ding Yang (CAU); 1 male 1 female, China, Tongliao, Daqinggou, 180 m, 2014.VII.22, Ning Wang & Ding Yang (CAU).

Distribution.

China (Inner Mongolia).

Remarks.

The new species is somewhat similar to the members of H. crassivena group, but the veins of H. triangulatus are not thickened (Zhang and Yang 2007).

Etymology.

This species is named after the triangular cercus.