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 1. Batraxis bicolor Wang and Yin , new species ( Figs 1 A, 5A, 5G, 6A–C) Type material (3 ♂♂, 1 ♀). Holotype : CHINA : ♂, labeled ‘ CHINA : Hainan, Qiongzhong Hsien (¼φθ), Limu Mt. (ϔDzM), nr. residence, 19°10'04"N , 109°44'45"E , decaying log, 625 m , 29.i.2015 , Peng, Yin, Tu, Song, Shen, Zhou, Yan, Wang leg.’. Paratypes : CHINA : 1 ♂ , 1 ♀, same label data as holotype ; 1 ♂ , also in Limu Mt., path to peak, 19°10'27"N , 109°45'29"E , mixed forest, decaying log, 1000 m , 31.i.2015 , Peng, Yin, Tu, Song, Shen, Zhou, Yan, Wang leg.’. Diagnosis of male. Body glabrous, elytra and abdomen with sparse, short setae; frons with complete subantennal transverse sulcus; vertex lacking median pit; antennomeres IX slightly transverse; pronotum with distinct median antebasal fovea and basal impression; all tibiae somewhat expanded; protibiae protuberant near apex, mesotibiae lacking apical spur; protrochanters protuberant ventrally; tergite IV with broad, abrupt basal sulcus; discal carinae long, widely separated; with complete marginal carinae; aedeagus elongate. Description. Male ( Fig. 1 A). Body reddish-brown to dark-brown, length 1.91 mm . Head rectangular, as long as broad, HL 0.40 mm , HW 0.40 mm , vertex glabrous, apical margin of frons and clypeus sparsely pubescent; vertex moderately convex, with pair of small but distinct vertexal foveae; antennal tubercles low; frons flattened, with complete subantennal transverse sulcus, lacking vertexal sulcus; each eye composed of about 30 facets; antennae relatively thick, antennomeres III slightly elongate, IV–VIII as long as wide, IX slightly transverse, narrower at base than at apex, X transverse, XI largest, widest near base, then obliquely narrowing toward apex; median gular carina narrow, with two clearly separated distinct nude gular foveae. Pronotum slightly wider than long, PL 0.37 mm , PW 0.42 mm , glabrous, with distinct nude median antebasal fovea and complete basal impression. Elytra wider than long, EL 0.40 mm , EW 0.77 mm , dorsal surface with sparse, short setae, with two pairs of distinct foveae at base. Protrochanters strongly protuberant at ventral margin ( Fig. 5 G), protibiae with small tooth near apex ( Fig. 5 A), expanded at middle; mesotibiae expanded at basal fourth and apical third, metatibiae expanded at basal fourth and apex. Abdomen darkish-brown, slightly wider than long, AL 0.74 mm , AW 0.76 mm , distinctly narrowed at base; tergite IV (first visible tergite) sparsely pubescent, with broad, abrupt basal sulcus; discal carinae relative elongate, widely separated, extending to one-third of tergal length, width between discal carinae 0.37 mm at apices; with complete marginal carinae. Aedeagus ( Fig. 6 A–C) 0.52 mm in length, elongate, parameres elongate, narrowed apically, each with one, long preapical seta; endophallus with two pairs of elongate sclerites and a weakly sclerotized median sclerite. FIGURE 1. Dorsal habitus of Batraxis species. A. B. bicolor . B. B. tibialis . Scale line: 0.3 mm. Female. Very similar to male in general appearance; protrochanters and tibiae lacking spur or expansion; each eye composed of about 30 facets. Measurements: BL 2.06 mm ; HL 0.44 mm ; HW 0.42 mm ; PL 0.38 mm ; PW 0.44 mm ; EL 0.48 mm ; EW 0.87 mm ; AL 0.76 mm ; AW 0.77 mm ; width between discal carinae of tergite IV 0.36 mm at apices. Comparative notes. Batraxis bicolor is similar to B. splendida Nomura , sharing the complete subantennal transverse sulcus of the head, partially expanded tibiae, setose mediobasal impression of the abdominal tergite IV, and elongate aedeagus. The two species can be separated by the presence of the small preapical tooth on the protibiae, reddish-brown head, pronotum, and elytra, and dark-brown abdomen, relatively larger head in comparison with the pronotum, and aedeagus with almost symmetric endophallus in the new species. In B . splendida the protibiae lack a preapical tooth, the body is uniformly colored, the head is relatively smaller in comparison with the pronotum, and the aedeagal endophallus is distinctly asymmetric. Distribution. Southern China : Hainan. Etymology. The specific epithet refers to the different colors of the elytra and the abdomen.