Two new species of Batriscenellus Jeannel from tropical Asia (Coleoptera Staphylinidae: Pselaphinae) Author Yin, Zi-Wei Laboratory of Systematic Entomology, College of Life Sciences, Shanghai Normal University, 100 Guilin Road, Xuhui District, Shanghai 200234, China. Author Kleeberg, Andreas Zum Alten Windmühlenberg 26, D- 12524 Berlin, Germany. text Zootaxa 2020 2020-08-04 4822 1 121 126 journal article 9164 10.11646/zootaxa.4822.1.7 5332fb9b-649a-43ab-934e-bd44824a678f 1175-5326 4401357 86E8756E-E9AA-4789-96E3-0595B0C40E0C Batriscenellus vietnamicus Yin & Kleeberg , sp. nov. ( Figs 1B , 3 ) Type material. HOLOTYPE : VIETNAM : ♂ , ‘N-Vietnam, Vinh Phuc Provinz , Dam Vac Lake , 11.4.2010 , lg. Kleeberg’ ( MNB ). Diagnosis. Male: dorsal surface of head and pronotum finely punctate. Head with thin median carina extending from posterior margin of vertex to level of anterior margin of eyes; trichomes on anterolateral margins of antennomeres 1 distinct. Pronotum with slightly sinuate lateral longitudinal sulci. Abdominal tergite 1 (IV) with small and deep posteromedian cavity. Aedeagus with large basal capsule, ventral lobe shorter than dorsal lobe. Description. Male ( Fig. 1A ). Body yellowish-brown, length (from anterior margin of clypeus to posterior margin of abdomen) 1.76 mm . Head sub-quadrate, length from anterior margin of clypeus to posterior margin of vertex 0.38 mm , width across eyes 0.41 mm ; dorsal surface ( Fig. 3A ) smooth and finely punctate, frons smooth; antennal tubercles moderately prominent; vertexal foveae nude, distinct, situated at level of middle of eyes, anterior margin of transverse vertexal sulcus slightly curved, posterior margin of sulcus carinate; antennae elongate, length 0.93 mm , clubs weakly indicated by apical three antennomeres; ocular-mandibular carina distinct; eyes strongly prominent, each composed of 30 large ommatidia. Pronotum ( Fig. 3A ) about as long as wide, length along midline 0.39 mm , maximum width 0.40 mm ; disc finely punctate; lateral longitudinal sulci slightly sinuate; with two very small, antebasal denticles. Elytra slightly wider than long, length along suture 0.59 mm , maximum width 0.69 mm ; discal striae extending to apical 4/5 of elytral length; with distinct humeral calli; with complete marginal striae originating from small subhumeral foveae. Legs elongate and slender, dorsal area of profemora with short sensory setae. Abdomen ( Fig. 3B ) wider than long, length along midline 0.45 mm , maximum width at middle of tergite 1 (IV) 0.59 mm ; tergite 1 (IV) longer than 2–4 (V–VII) combined, with small and deep median cavity in posterior half of tergite, anterior to cavity there are two longitudinal impressions at sides and one semicircular impression at middle, anterior margin of cavity with forked, semi-membranous structure and pair of short bunches of setae, one small nodule at posterior margin of cavity, with bunch of setae on anterior margin of nodule, areas lateral to cavity sparsely covered with sensory setae; discal carinae lengthily triangular, widely separated; single marginal carina extending posteriorly to 1/3 of tergal length; weakly sclerotized sternite 7 (IX) ( Fig. 3C ) transverse, suboval. Aedeagus ( Fig. 3 D–F) asymmetric, length 0.35 mm ; basal capsule (somewhat collapsed and partial broken in holotype ) strongly dilated; ventral lobe short and broad, abruptly acute at right side in ventral view of apex; dorsal lobe much longer than ventral lobe, composed of one long and one much shorter sclerite, long one broad at base and narrowing to apex, moderately curved to right in ventral view; parameres fused to form short ventral membrane. Female. Unknown. FIGURE 3. Diagnostic characters of Batriscenellus vietnamicus , male. A. Head and prothorax, dorsal. B. Abdomen, dorsal. C. Sternite 7 (IX). D–F. Aedeagus, in axial (D), ventral (E), and lateral (F) view. Scale bars: 0.2 mm in A, B; 0.05 mm in C; 0.1 mm in D–F. Comments. The small size and the position of the tergal cavity of the new species are shared with Batriscenellus abdominalis Yin & Wang from Zhejiang and B . fanxingqiui Jiang & Yin from Fujian , eastern China . Batriscenellus vietnamicus can be readily separated from B . abdominalis by the finely punctate head and pronotum, which are rather coarse in the latter species. Also, the structure of the aedeagus of the new species is similar to that of B . fanxingqiui , indicating a close affinity between these two species. However, a different configuration of the tergal cavity and the structure of the aedeagus, as well as the distributions, easily separate them. Distribution. Vietnam : Vinh Phuc . Etymology. The new specific epithet refers to the country where the type locality of the new species is located.