Batrisiella beibeng, Yin, 2022

Yin, Zi-Wei, 2022, The Batrisini of Tibet: unveiling an enigmatic ant-loving beetle diversity at Earth’s “ Third Pole ” (Coleoptera, Staphylinidae, Pselaphinae), Zootaxa 5111 (1), pp. 1-211 : 74-76

Batrisiella beibeng sp. nov.

( Figs 31 , 80B , 99A )

Chinese common name: Ü崩小毛唇à甲

Type material (23 exx.). HOLOTYPE: CHINA: ♂, ‘China: Xizang, Mêdog County, nr. Beibeng , 29°14’11”N, 95°09.54”E, 825 m, 11.vii.2018; mixed leaf litter, sifted, Cheng, Peng Shen leg., [Ʊ ẪẸṘÜ 崩乡]’ ( SNUC) . PARATYPES: CHINA: 7 ♂♂, 15 ♀♀, same data as that of holotype ( SNUC) .

Diagnosis. Male. Body length 1.82–1.85 mm. Head sub-rectangular at base; vertexal foveae moderately large and asetose, lacking sulcus connecting them; antenna moderately elongate; antennomeres each elongate, 9–11 enlarged to form indistinct club. Discal stria of elytron extending to approximately apical 1/8 of elytral length. Legs with profemur markedly thickened at distal 1/2, with disc-like protuberance at apical 1/4 on dorsal surface, metatibia broadened at distal 1/2. Aedeagus strongly asymmetric; median lobe with large basal capsule, lacking basoventral projection, ventral stalk curved rightwards in ventral view (position in figure); dorsal lobe strongly curved for whole length, forked apically; parameres reduced to single, weakly membranous structure. Female. Body length 1.80–1.86 mm; antenna shorter, legs lacking modifications, genitalia as in Fig. 31K .

Description. Male. Body ( Fig. 31A ) length 1.82–1.85 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 31B ) sub-rectangular at base, slightly broader than long, length 0.38–0.39 mm, width across eyes 0.41–0.42 mm; vertex finely punctate, with moderately large, asetose vertexal foveae (dorsal tentorial pits), lacking U-shaped sulcus connecting foveae or mediobasal carina, with transverse, medially emarginate sulcus between antennal tubercles; antennal tubercles moderately raised; frons broadly impressed medially, demarcated from clypeus by nearly complete frontal-clypeal ridge; clypeus with rough surface, its anterior margin carinate and moderately raised; ocular-mandibular carina complete. Venter with two small gular foveae (posterior tentorial pits) close originating from shared opening, with thin median carina extending from foveae anteriorly to mouthparts. Compound eyes prominent, composed of approximately 30 ommatidia. Antenna moderately elongate, length 0.96–0.98 mm, apical three antennomeres forming indistinct club; antennomere 1 thick, subcylindrical, apicolateral portion with large internal glandular structure, indistinct, 2–8 each elongate, 8 smallest, 9 much larger than 8, 10 as long as and slightly broader than 9, 11 largest, slightly shorter than 9 and 10 combined, sub-fusiform.

Pronotum ( Fig. 31B ) approximately as long as broad, length 0.43–0.45 mm, width 0.42 mm, widest at middle; lateral margins rounded; disc slightly convex, finely punctate, pubescent, median longitudinal sulcus as long as semicircular lateral sulci in dorsal view, the latter extending from dorsal surface laterally and posteriorly and then fusing with lateral ends of antebasal sulcus; lacking median antebasal fovea, lateral antebasal foveae connected by transverse antebasal sulcus, with small antebasal spines; outer and inner pair of basolateral foveae distinct. Prosternum with anterior part slightly longer than coxal part, with distinct lateral procoxal foveae; hypomeral ridge extending from base to middle of anterior part, with punctiform lateral antebasal hypomeral pit; margin of coxal cavity weakly carinate.

Elytra much wider than long, length 0.53–0.55 mm, width 0.67–0.69 mm; each elytron with two large, asetose basal foveae, lacking subbasal fovea; discal stria extending from outer basal fovea to approximately apical 1/8 of elytral length; humerus angulate, small subhumeral fovea present, sulcate marginal stria extending posteriorly from fovea to elytral posterior margin and anteriorly to dorsal surface of elytron.

Mesoventrite short, demarcated from metaventrite by ridged anterior edges of impressed areas where lateral mesocoxal foveae situated at mesal margins, with pair of thin admesal carinae; setose median mesoventral foveae widely separated, lateral mesoventral foveae large and setose, broadly forked internally; intercoxal process short. Metaventrite longitudinally sulcate along midline, with large, setose lateral mesocoxal foveae and pair of smaller, setose lateral metaventral foveae, posterior margin emarginate at middle, lacking split.

Legs elongate; profemur ( Fig. 31C ) strongly thickened at distal 1/2, dorsal surface ( Fig. 31D ) near apex with disc-like protuberance, metatibia ( Fig. 31E ) expanded at distal 1/2, surface with dense short setae.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.48–0.53 mm, width 0.63–0.65 mm. Tergite 1 (IV) longer than tergites 2–4 (V–VII) combined in dorsal view, setose basal sulcus separated by two mediobasal and one pair of basolateral foveae, with pair of short discal carinae, marginal carina present only at basal 1/2; tergites 2–4 (V–VII) tightly compressed, each with one pair of basolateral foveae, tergite 4 (VII) shorter than 2 and 3 combined along middle, tergite 5 (VIII) broad and slightly transverse. Sternite 2 (IV) with large mediobasal and pair of broad, setose basolateral sockets, with long lateral carinae, midlength slightly longer than 3–4 (V–VI) combined, sternites 3–5 (V–VII) each with one pair of indistinct basolateral foveae, sternite 6 (VIII) with posterior margin slightly emarginate, sternite 7 (IX) ( Fig. 31F ) asymmetric, transversely slightly oval, weakly sclerotized at apical part.

Aedeagus ( Fig. 31G–J ) 0.25 mm long, strongly asymmetric; median lobe with large basal capsule and sub-triangular foramen, lacking basoventral projection, ventral stalk narrowing towards apex, curved rightwards in ventral view (position of figure); dorsal lobe elongate, strongly curved, apex split into two unequal thin lobes, dorsal part with additional spine-like lobe; parameres reduced to single weakly membranous structure.

Female. Similar to male in external morphology; antenna shorter; each compound eye composed of approximately 20 ommatidia; humerus also prominent; legs lacking modifications. Measurements (as for male): body length 1.80–1.86 mm; length/width of head 0.36–0.38/ 0.40 mm, pronotum 0.43–0.44/ 0.42 mm, elytra 0.48–0.50/ 0.64–0.69 mm; abdomen 0.52–0.56/ 0.62–0.65 mm; length of antenna 0.85–0.90 mm; maximum width of genitalia ( Fig. 31K ) 0.19 mm.

Comparative notes. The new species shares with B. acclivis the broad male profemora, but differs by the femora lacking dense setae and with a disc-like protuberance, the thickened male metatibiae, as well as a generally more elongate aedeagus with a slenderer ventral stalk of the median lobe. The modified profemora are also shared by B. strictus Jiang & Yin which is distributed in Guangxi, southern China. Apart from this, the two species can be readily separated by the lack of a mediobasal carina of the vertex, the much longer discal carinae of the elytra, and the distally broadened metatibiae (normally slender in B. strictus) of the new species.

Distribution. Mêdog County, Tibet, SW China ( Figs 80B , 99A ).

Etymology. The specific epithet refers to the type locality of the new species, i. e., Beibeng Township.

Figures

FIGURE 31. Morphology of Batrisiella beibeng sp. nov. (A–J. Male. K. Female). A. Dorsal habitus. B. Head and pronotum. C. Profemur. D. Apical part of profemur, enlarged. E. Metatibia. F. Sternite 7 (IX). G–J. Aedeagus, dorsal (G), lateral (H), ventral (I) and anterior (J). K. Genitalia. Scale bars: 0.5 mm in A; 0.2 mm in B, C, E; 0.05 mm in F; 0.1 mm in G–K.

FIGURE 80. Distribution of Tibetan Batrisini. A. Batriscenaulax campestris sp. nov. B. Batrisiella acclivis sp. nov. (circle), B. beibeng sp. nov. (triangle), B. bomea sp. nov. (square) and B. concisa sp. nov. (cross). C. B. curvitibialis sp. nov. (circle), B. ganma sp. nov. (triangle), B. guttata sp. nov. (square) and B. zhujianqingi (diamond).

FIGURE 99. Environment of and collecting sites at Nyingchi area. A. Beibeng Township (Ü崩乡). B. Road near Gelin Village (格ff村). C. A bridge at Yarang (亚ü). D. A village near Guoguotang Great Bend (果果Ƌkm弯). E. Environment near Mêdog County (ẸṘ县). F. Path to Renqingbeng Temple (仁ů崩寺). G. An overall view of Guoguotang Great Bend. Photo Credit: E, F by Xiao-Bin Song.