Zaitzevia chenzhitengi Jiang & Wang sp. nov.

Figs 1A, 2, 4 A–C, G, I, K–L

Type material: Holotype: CHINA: ♂, labeled ‘ China: Sichuan, Lixian County, side of Xuemeng Road, a small unnamed stream, 31°33′56′′N, 103°17′32′′E; H: 1634m, 05.10.2019, Zhi-Teng Chen leg.’ (QUST). Paratype: 1 ♀, with same label data as the holotype (QUST).

Description. Male. Body elongate elliptical (Fig. 1A), dark brown, tibiae, tarsi, tarsal claws and antenna reddish-brown, dorsal surface punctate, covered with sparse setae. Lateral margins of elytra covered with dense short setae. Silvery sericeous tomentum is confined to following areas: head (both dorsal and ventral surface), pronotum, prosternum, outer part of elytra (include epipleura), outer parts of mesosternum, metaventrite and abdomem (except median part) and surface of femora.

Head (Fig. 2A), wider than long, dorsal surface covered with dense short setae and sparse big punctures, each puncture with a much longer seta, the interspaces tbetween the punctures about 1.5–2 times diameters of punctures. Clypeus evenly punctate with large punctures and covered with sparse long setae. Labrum transverse, shorter and broader than clypeus, covered with big punctures and long bristles at apical portion, anterior margin almost straight and anterolateral angles rounded. Antenna (Fig. 2C) short, with eight antennomeres; antennomere I slightly longer than wide, with several short setae; II much longer than I, expanded, covered with several long setae, apical margin circled with short setae; III longer than wide; IV-VII strongly transverse; VIII elliptical, elongate and strongly expanded, apex covered with dense long setae.

Pronotum (Fig. 2B) slightly wider than long, widest near basal 1/3. Anterior margin arcuate with angles moderately produced and acute. Lateral margins finely curved. Basal margin trisinuate, emarginate before scutellum, posterior angles obtuse. Surface shiny, covered with sparse big punctures, each puncture with a much longer than what seta; surface near apical angles microreticulate. Distinct longitudinal impression in the middle of the pronotum; sublateral carinae from base to 1/2, slightly curved. Prosternal process (Fig. 2D) with rounded apex.

Elytra (Fig. 2F) about twice as long as wide, subparallel in anterior 2/3, surface finely wrinkled and covered with sparse long setae. Each elytron with granulate carinae on strial intervals 5, 7 and 8, other intervals flat. Area from intervals to lateral margin covered with dense short setae. Hind wings well developed.

Metaventrite (Fig. 2E), surface smooth and without setae on disc, sides with silvery sericeous tomentum. Median sulcus distinct, extending from posterior margin to ca. 3/4 of metasternum. Sides of median sulcus with a pair of distinct subglobular grooves near posterior margin; and a pair of anomalous shallow grooves near mesocoxae.

Abdomen with 5 visible sternites, sides of sternites with silvery sericeous tomentum. Sternites V and VI granulated; apex of sternite V (Fig. 4K)emarginate.

Legs simple, femora swollen, surface covered with sericeous tomentum; inner side of tibiae with cleaning fringes; tarsi about as long as tibiae; tarsal claws simple.

Aedeagus (Figs 4 A–C), slender and elongate, apex of median lobe characteristically arrowhead-like. Speculum gastrale as in Fig. 4G.

Measurements: BL: 3.03 mm; HL: 0.24 mm, HW: 0.53 mm; PL: 0.83 mm, PW: 0.92 mm; EL: 2.20 mm, EW: 1.06 mm.

Female: externally similar to the male, larger in size, apex of sternite V (Fig. 4L) rounded. Ovipositor as in Fig. 4I. Measurements: BL: 3.20 mm; HL: 0.26 mm, HW: 0.57 mm; PL: 0.90 mm, PW: 0.97 mm; EL: 2.30 mm, EW: 1.24 mm.

Distribution. China: Sichuan Province.

Biology. All adults were collected in the bottom crack of a stone in a small ravine stream (Figs 5 A–C).

Etymology. This species is named in honor of our friend Dr. Zhi-Teng Chen, an aquatic entomologist who collected the new species and donated it to us for study.

Comparative diagnosis. Zaitzevia chenzhitengi sp. n. is similar to the Japanese species Zaitzevia rivalis Nomura, 1963, both species share similar habitus, e.g. the relatively large and elongate oval-shape of body and the subequal length and width of pronotum. However, the new species can be well distinguished from the latter by the different body size (> 3mm in the new species, 2.1–2. 3 mm in Z. rivalis), and elytral surface of the new species is finely wrinkled whereas it’s smooth and lustrous in Z. rivalis (Nomura 1963). On other way, the Vietnamese species Zaitzevia pocsi Delève, 1968 also with a similar arrowhead-like apex of median lobe, it could be distinguished from the new species by the thinner apex of median lobe, the wider aedeagus, and the much smaller body size (1.62 mm).