Batrisiella ganma, 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 : 83-85

Batrisiella ganma sp. nov.

( Figs 35 , 80C , 93E–G )

Chinese common name: HḼ小毛唇à甲

Type material (11 exx.). HOLOTYPE: CHINA: ♂ , China: Xizang, Dinggyê County, Zhêntang Town, Ganma Zangbo Valley , 27°51’50”N, 87°24’24”E, 2400 m, 28.vi.2021, Z. Peng leg., ƱẪŤĠ县ĿƋWH玛Ẫ布河ě ’ ( SNUC) . PARATYPES: CHINA: 6 ♂♂, same data as that of holotype; 1 ♂, 3 ♀♀, also from Zhêntang , except ‘Xiuxiongma Vill., 27°54’11”N, 87°22’42”E, 2700-3000 m, 25.vi.2021, Z. Peng, Z. Yin & W. Zhang leg., ƱẪU 喀NJŤĠ县ĿƋWšŏ玛村 ’ (all paratypes in SNUC) .

Diagnosis. Male. Body length slightly over 1.65 mm. Head sub-rectangular at base; vertexal foveae moderately small and asetose, with transverse sulcus between antennal tubercles, lacking mediobasal carina; antenna moderately long, antennomeres slightly elongate, lacking modifications. Discal stria of elytron extending to apical 1/5 of elytral length. Legs almost simple, only mesotibia with tiny apical spur. Abdomen with large tergite 1 (IV) and vertical tergites 2–5 (V–VIII); tergite 1 with large posteromedial cavity and setose lateral patches. Aedeagus strongly asymmetric; ventral stalk narrowing apically and with rounded apex; dorsal lobe strongly twisted, in dorsal view expanded at apex; parameres reduced and forming single membranous structure. Female. Body length over 1.7 mm; mesotibia lacking apical spur, tergite 1 lacking modifications, genitalia as in Fig. 35G .

Description. Male. Body ( Fig. 35A ) length 1.66–1.67 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with moderately long pubescence.

Head ( Fig. 35B ) sub-rectangular at base, approximately as long as wide, length 0.36–0.38 mm, width across eyes 0.39–0.41 mm; vertex finely punctate, sparsely pubescent, with moderately small, asetose vertexal foveae (dorsal tentorial pits), with short, transverse sulcus between antennal tubercles, lacking median longitudinal sulcus; antennal tubercles moderately raised; frons with roughened surface slightly impressed between antennal tubercles, anterolateral margins carinate, medially confluent with clypeus; clypeus with roughened surface, its anterior margin moderately carinate and raised; ocular-mandibular carina present. Venter with two small gular foveae (posterior tentorial pits) originating from shared transverse slit, with distinct median carina extending from foveae anteriorly to mouthparts. Compound eyes prominent, composed of approximately 21 large ommatidia. Antenna elongate, length 0.88–0.92 mm, apical three antennomeres enlarged and forming moderately distinct club; antennomere 1 thick, subcylindrical, apicolateral portion with elongate inner glandular structure and indistinct trichome, 2–7 each elongate, 8 sub-moniliform, 9 much larger than 8, 10 slightly broader than and as long as 9, 11 largest, as long as 9 and 10 combined, sub-conical.

Pronotum ( Fig. 35B ) approximately as long as broad, length 0.42–0.43 mm, width 0.41–0.43 mm, widest at middle; lateral margins rounded; disc slightly convex, finely punctate and sparsely 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 deep antebasal sulcus; outer and inner pair of basolateral foveae distinct. Prosternum with anterior part as long as coxal part, with large 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 0.49–0.50 mm, width 0.66–0.70 mm; each elytron with two large, asetose basal foveae, lacking subbasal fovea; discal stria carinate, extending from outer basal fovea to apical 1/5 of elytral length; humerus weakly prominent, with small subhumeral fovea, with marginal stria extending from fovea to posterior margin 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, not forked internally; intercoxal process short. Metaventrite weakly impressed at middle, with large, setose lateral mesocoxal foveae and pair of smaller, setose lateral metaventral foveae, posterior margin broadly emarginate at middle, lacking split.

Legs moderately elongate, lacking distinct modifications; mesotibia with tiny apical spur.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.49–0.50 mm, width 0.65–0.70 mm. Tergite 1 (IV) ( Fig. 35C ) much longer than tergites 2–4 (V–VII) combined, setose basal sulcus separated by mediobasal and one pair of basolateral foveae, discal carina long, marginal carina absent; posteromedial cavity large, with fringed anterior margin projecting posteriorly at middle, inside cavity there is one mediobasal process and longitudinal row of dense setae, area lateral to cavity with large setose patch covered with dense, short setae; tergites 2–5 (V–VIII) tightly compressed, vertical, 2–4 each with one pair of basolateral foveae, 4 longer than 2 and 3 combined along middle, 5 broad and slightly transverse, posterior margin roundly emarginate at middle. Sternite 2 (IV) with large mediobasal foveae and large basolateral sockets in broad setose basal impression; midlength of sternite 2 (IV) approximately as long as 3–4 (V–VI) combined, sternites 3–5 (V–VII) each with one pair of small basolateral foveae, sternite 6 (IX) ( Fig. 35D ) rounded at apex, apical 1/3 weakly sclerotized and with a few setae along anterior margin, basal 2/3 membranous.

Aedeagus ( Fig. 35E, F ) 0.31 mm long, strongly asymmetric; median lobe with large basal capsule and rounded triangular foramen, ventral stalk narrowing apicad and with rounded apex in dorso-ventral view; dorsal lobe transversely protruding and then strongly curved and expanded apically; parameres reduced and forming single membranous structure.

Female. Similar to male in external morphology; antenna shorter; tergite 1 (IV) lacking modifications; each compound eye composed of approximately 15 ommatidia; humeral angle rounded; mesotibia lacking apical spur. Measurements (as for male): body length 1.70–1.71 mm; length/width of head 0.37–0.38/ 0.39–0.40 mm, pronotum 0.42–0.43/ 0.41–0.42 mm, elytra 0.47–0.48/ 0.68–0.70 mm; abdomen 0.57–0.58/ 0.67–0.70 mm; length of antenna 0.84–0.87 mm; maximum width of genitalia ( Fig. 35G ) 0.19 mm.

Comparative notes. The new species is close to B. concisa by sharing a similar placement and the form of the male tergal modification and the aedeagus. Batrisiella ganma can be readily separated from B. concisa by the lack of a median longitudinal sulcus on the vertex of the head (sulcus broad and deep in B. concisa ).

Distribution. Dinggyê County, Tibet, SW China ( Figs 80C , 93E–G ).

Etymology. The new species is name after Ganma (= Gama) Zangbo, a river lying south of Zhêntang Town.

Figures

FIGURE 35. Morphology of Batrisiella ganma sp. nov. (A–F. Male. G. Female). A. Dorsal habitus. B. Head and pronotum. C. Tergite 1 (IV). D. Sternite 7 (IX). E, F. Aedeagus, lateral (E) and ventral (F). G. Genitalia. Scale bars: 0.5 mm in A; 0.2 mm in B, C; 0.05 mm in D; 0.1 mm in E–G.

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 93. Environment of and collecting sites at Zhêntang Valley (ĿƋ沟). Slopes at altitudes of 3700 m (A), 4000 m (B), and 3050 m (C). D. Nadang Village (Ḅ当村). E. Road to Xiuxiongma Village (šŏ玛村). F, G. Environment of Ganma Zangbo Valley (HḼẪ布河ě). Photo Credit: F, G by Zhong Peng.