On a collection of Batraxis Reitter (Coleoptera: Staphylinidae: Pselaphinae) from Hainan Island, southern China Author Wang, Dan Author Yin, Zi-Wei Author Wang, Chun-Xin text Zootaxa 2016 4109 1 1 15 journal article 39133 10.11646/zootaxa.4109.1.1 4dcea233-45e7-4c56-a91c-e97d6c250262 1175-5326 258822 5AA87F55-DE88-419B-98D4-ECDC3AE09FAE 7. Batraxis simplex Wang and Yin , new species ( Fig. 4 A–E) Type material (5 ♂♂, 11 ♀♀). Holotype : CHINA : ♂, labeled ‘ CHINA : Hainan, Ledong Hsien, Jianfengling N.R., Mingfenggu, 18°44'30"N , 108°50'29"E , rainforest, decaying log, 995 m , 27.i.2015 , Peng, Yin, Tu, Song, Shen, Zhou, Wang leg.’ Paratypes : CHINA : 1 ♂ , 6 ♀♀, same label data as holotype ; 3♂♂, 2♀♀, same data as previous except ‘ 23.i.2015 ’; 3 ♀♀, same data as previous material except ‘ 26.i.2015 ’. Diagnosis of male. Body with sparse, minute pubescence in most areas; frons with complete subantennal transverse sulcus; vertex lacking median pit; antennomeres IX as long as wide; pronotum with distinct median antebasal fovea and basal impression; all tibiae thin; protibiae lacking modification, mesotibiae without apical spur; protrochanters simple; tergite IV with broad basal sulcus; discal carinae long, widely separated; with complete marginal carinae; aedeagus relatively stout. Description. Male ( Fig. 4 A). Body reddish brown, with sparse minute pubescence, length 2.01 mm . Head rectangular, slightly longer than wide, HL 0.44 mm , HW 0.42 mm , vertex moderately convex, vertexal foveae small but distinct, with a V-shaped vertexal sulcus connecting foveae; antennal tubercles low; frons flattened, subantennal transverse sulcus complete, anterior margin of vertexal sulcus merging with subantennal transverse sulcus; each eye composed of about 30 facets; antennae relatively thick, antennomeres III–VII slightly elongate, VIII‒IX as long as wide, X transverse, XI largest, widest near base, then obliquely narrowing toward apex; median gular carina narrow, with two close small gular foveae. Pronotum slightly wider than long, PL 0.40 mm ; PW 0.45 mm , with distinct median antebasal fovea and complete coarse basal impression. Elytra wider than long, EL 0.55 mm , EW 0.78 mm , with two pairs of shallow foveae at base. Protrochanters lacking spur ( Fig. 5 E). Abdomen wider than long, AL 0.62 mm , AW 0.72 mm , distinctly narrowed at base; tergite IV (first visible tergite) with broad, abrupt basal sulcus; discal carinae long, widely separated, extending to half of tergal length, width between divergent discal carinae 0.44mm at base, 0.52 mm at apices; marginal carinae complete. Aedeagus ( Fig. 4 B–D) 0.37 mm in length, relatively stout, parameres widest at middle, each with three preapical setae; endophallus complicated, with a series of symmetric sclerites, and numerous spine-like structures apicomedially. Female. Very similar to male in general appearance; each eye composed of about 30 facets. Measurements: BL 1.89 mm ; HL 0.44 mm ; HW 0.42 mm ; PL 0.40 mm ; PW 0.44 mm ; EL 0.50 mm ; EW 0.76 mm ; AL 0.55 mm ; AW 0.69 mm ; width between divergent discal carinae of tergite IV 0.52mm at base, 0.39 mm at apices. FIGURE 4. Diagnostic features of male Batraxis simplex . A. Dorsal habitus. B. Aedeagus, in dorsal view. C. Same, in later view. D. Same, in ventral view. E. Protrochanter. Scale line: A = 0.3 mm; B, C, D, E = 0.05 mm. Comparative notes. The widely separated discal carinae of tergite IV in the new species is shared with B . bicolor , B . tibialis , and B . pilosa . Batraxis simplex can be readily separated from all above congeners by the presence of a V-shaped vertexal sulcus, coarse basal collar of the pronotum, and structure of the aedeagus. Distribution. Southern China : Hainan. Etymology. The specific epithet refers to the lack of obvious modifications in the male.