Rhaphium bilobum sp. nov.

(Figs 2, 9–10)

Diagnosis. First flagellomere 10.5 times longer than wide; arista black, 0.23 times as long as first flagellomere (Fig. 9). Five dc. All coxae yellow except mid coxa black dorsally and ventrally, hind coxa blackish at basal 1/4. Cercus bifoliate, ventral lobe long strip-like, in equal width from base to tip, 1.3 times as long as epandrium; dorsal lobe oval, short, 2/3 as long as epandrium.

Description. Male (Fig. 2). Body length 2.5–3.0 mm, wing length 2.7–3.2 mm. Head: Frons metallic green with grey white pollinosity; face dark metallic green with thick silvery white pollinosity, nearly as wide as first flagellomere; palpus and proboscis black with black hairs, palpus with 1 black apical bristle; bristles and hairs on head black except postocular bristles and posteroventral hairs pale yellow; antenna black; first flagellomere nearly isosceles triangular, somewhat elongated, rounded at tip, 10.5 times longer than wide; arista apical, simple, with short pubescence, 0.23 times as long as first flagellomere (Fig. 9). Thorax metallic green with grey white pollinosity; propleuron covered by short pale yellow bristles; metapleuron yellowish brown at lower portion narrowly; hairs and bristles strong and black; 5 strong dc; 5–6 pairs of short irregular acr; lateral sc weak and short. Legs mainly yellow, all coxae yellow except mid coxa black dorsally and ventrally, hind coxa blackish at basal 1/4; tarsomeres 5 black. Hairs and bristles on legs black except coxae with pale yellow anterior hairs, mid coxa with 1 black outer bristle at middle, hind coxa with 1 black outer bristle. Fore femur with 1 pv close to base and 2 rows of sparse irregular bristles. Mid femur with 1 preapical ad. Hind femur without distinct bristle. Fore tibia with 1 ad at basal 1/3; mid tibia with 1 ad, 2 pd and 3 apical bristles; hind tibia with 1 ad, 2 pd and 3 apical bristles. Relative length ratio from tibia to tarsomere 5: LI: 6.0/4.0/2.0/1.0/0.7/0.6, LII: 8.0/4.5/2.3/1.0/0.7/0.6, LIII: 6.0/2.0/1.0/0.5/?/? (hind tarsus broken). Wing hyaline, somewhat brownish; veins dark brown, R4+5 and M somewhat convergent apically; CuAx ratio 0.4. Squama yellow, with fan of pale white bristles; halter pale. Abdomen metallic green with grey white pollinosity. Bristles and hairs black. Segments 1–5 with pale yellow hairs laterally, sternites 1–4 with pale yellow hairs. Male genitalia (Fig. 10): epandrium nearly as long as wide. Surstylus digitiform, thinner onwards at apical 1/3 portion, inflated at middle with 1 rounded incision. Cercus black, bifoliate, ventral lobe long strip-like, in equal width from base to tip, 1.3 times as long as epandrium, with short strong marginal bristles; dorsal lobe oval, short, 2/3 as long as epandrium, with long marginal bristles. Hypandrium simple, slightly inflated apically; phallus simple, thin at apical portion. Female. Body length 3.0 mm, wing length 3.0 mm. Similar to male except first flagellomere small, 1.3 times longer than wide.

Type material. HOLOTYPE, Ƌ labeled: China: Inner Mongolia, Daqinggou, Primeval forest (N42°82′18″ E122°17′41″), 180 m, collected by sweeping net in grass and brushes, 2014. VII.23, N. Wang & D. Yang (CAU) . PARATYPES: 8 Ƌ 3 ♀, same data as holotype.

Distribution. Palaearctic: China (Inner Mongolia).

Remarks. The new species is somewhat similar to R. zhongdianum Yang & Saigusa, 2001 from Yunnan province of China, but may be separated from the latter by the length / width ratio of the first flagellomere, the color of legs and the shape of the cercus. In R. zhongdianum, the first flagellomere is 8.0 times longer than wide; the legs are mainly yellow, but the mid and hind coxae are black except the extreme apex; the cercus is deeply bifurcated with 2 long lobes (Yang & Saigusa, 2001).

Etymology. The word ‘ bilobum’ means bifoliate. The new species is named after the shape of cercus.