Lasioglossum (Sudila) genotrigonum Zhang et Zhu, sp. nov.

(Figs. 3–8)

Diagnosis. This species can be distinguished from all other Sudila species by the following combination of characters: body black; metasomal tergum brown apically; hairs sparse; punctures fine, especially on mesoscutum; genal area nearly triangular, margin angulate, as wide as eye; basal 2/3 of propodeal dorsum with longitudinal ridges.

Description. Female. BL= 7.9 mm. Body black without metallic tint; apical of mandible, flagellum and wing vein dark brown; tegula, tarsus except basitarsus, and apical of metasomal tergum brown; tibial spur fawn; wing brown and transparent. Hairs whitish and sparse; apical of clypeus with a raw simple, yellowish brown bristles; eye with glabrous hairs; lateral surface of propodeum with dense plumose hairs; tibia, basitarsus and apical of T5 with yellowish brown hairs; tergum without patch, with sparse simple plumose hairs; scopa well developed.

Head longer than wide. Labrum with tubercle basally. Anterior margin of clypeus truncate, clypeal tooth mild, anterior with fastigiated punctures nearly forming longitudinal furrows; punctures on supraclypeal area fine, IS= 3– 4; sculptures on ocellocular area disɭΓibuɭed equƋb|ʸ, IS= 1; punctures on frons area coarse, IS= 0.5; frontal carina distinct, exceeding the lower margin of anterior ocellus; inner upper margin of eyes concave, lower convergent; scape reaching the half of lateral ocellus. Frontal view of head as in Fig. 3. Seen laterally, genal area nearly triangular, margin angulate (Fig. 4), EW: GW= 24: 25, above finely and sparsely punctate, IS= 3; HL: HW= 37: 34; IOD: OOD: Od: OCD= 15: 17: 12: 9; UOD: MOD: LOD= 24: 30: 23; scape L: pedicel L: F1L: F2L: F3L: F4L: F5L: F6L: F7L: F8L: F9L: F10L= 43: 7: 7: 3: 4: 5: 7: 8: 8: 8: 9: 13; F2L: F2W= 4: 7. Antenna as in Fig. 5.

Mesoscutum and scutellum with fine punctures, IS= 3–4, posterior area coarser (Fig. 15 A); medianmesoscutal line and parapsidal line distinct; mesepisternum finely granular, upper area with transverse striation, lower area with a characteristic tubercle (Fig. 6); metepisternum, lateral surface of propodeum with transverse striation; propodeal dorsum truncate apically, basal 2/3 with longitudinal ridges as in Fig. 7 and Fig. 15 C; the lateral and posterior surfaces of propodeum not separated by carina; MCL: MTL: PDL= 43: 15: 27.

WL= 7.2 mm. Fore wing with veins 1r-m, 2r-m, 2m-Cu, and M-b narrower than Rs-a and M-a; 2r-m, 2m-Cu and M-b narrower than 1r-m; hamuli arranged in 2-1-2.

Basitibial plate elongate oval, pointed apically; inner hind tibial spur with 4 distinct, fastigiated, pectinate teeth (Fig. 8).

Metasoma elongate oval. Posterior areas of T1–T5 straight forwards with transverse weak wrinkle. T1 with fine and sparse punctures, nearly smooth anteriorly, middle area IS= 1; T2 medially as coarse as T1, laterally finer; T3 and T4 IS= 2–3; T5 IS= 2; T6 hidden in T5 below, with U-shaped pygidial plate; sting L= 1.5 mm.

Male. Unknown.

Type material. Holotype, Ƥ, China, Chongqing, Wanzhou District, Wan Er bao Nature reserve, 30°80ʹN 108°40ʹE, 1200m, 11 July 1993, Jian Yao. Paratype, 1Ƥ, China, Chongqing, Wanzhou District, Wan Er bao Nature reserve, 30°80ʹN 108°40ʹE, 1200m, 11 July 1993, Jian Yao.

Type series are deposited in the Insect Collections of Institute of Zoology, Chinese Academy of Sciences, Beijing, China.

Distribution. China (Chongqing).

Etymology. The name genotrigonum is derived from the Greek gen- (= genal) and Greek trigonum (= triangular), referring to genal area nearly triangular.