Tribasodites gyirong, 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 : 159-161

Tribasodites gyirong sp. nov.

( Figs 68 , 86B , 89 )

Chinese common name: 吉Pûḃà甲

Type material (11 exx.). HOLOTYPE: CHINA: ♂ , ‘ China: Xizang, Gyirong County, Gyirong Valley , pass nr. Jifu Vill., 28°21’35”N, 85°20’46”E, 2600–2700 m, 19.vi.2021, Z. Peng, Z. Yin & W. Zhang leg., ƱẪU喀NJ吉PW吉 ė村ṉữ山ě ’ ( SNUC) . PARATYPES: CHINA: 4 ♂♂, 6 ♀♀, same data as that of holotype ( SNUC) .

Diagnosis. Male. Body length over 2.6 mm. Head subtruncate at base, slightly narrower than pronotum, tempus moderately short, rounded at posterolateral angle, vertex with transverse impression at apex, with relatively large, asetose foveae, with distinct mediobasal carina extending from head base anteriorly beyond level of posterior margin of eyes, with distinct lateral carina from head base to posterior margin of antennal tubercle; antenna elongate, with modified antennomeres 10–11, antennomere 11 with distinct basal projection. Pronotum with laterally carinate median and lateral longitudinal sulci, with pair of discal carinae, with two pairs of antebasal and distinct marginal spines. Discal stria of elytron long, extending posteriorly to approximately apical 1/4 of elytral length; disc finely punctate. Mesotibia with large, blade-like apical projection. Aedeagus strongly asymmetric; median lobe with extended basal capsule and elongate foramen, ventral stalk broad at middle and then abruptly narrowing and protruding apically, with forked apex, dorsal lobe large, plate-like, with elongate sclerite narrowing towards apex. Female. Body length slightly over 2.5 mm, antenna shorter than male, antenna and legs lacking modifications, genitalia as in Fig. 68K .

Description. Male. Body ( Fig. 68A ) length 2.68–2.78 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with relatively dense pubescence.

Head ( Fig. 68B ) roundly at base, much wider than long, length 0.52 mm, width across eyes 0.60 mm; vertex smooth, with transverse impression at apex, vertexal foveae (dorsal tentorial pits) asetose, relatively large, mediobasal carina distinct, extending from head base anteriorly to slightly beyond level of posterior margin of eyes, lateral carina distinct, extending from base to posterior margin of antennal tubercle; posterolateral margin rounded; frons weakly impressed between large, moderately raised antennal tubercles, anteriorly demarcated from clypeus by oblique frontal-clypeal ridge; clypeus with smooth surface, its entire anterior margin strongly carinate and moderately raised; ocular-mandibular carina complete, carina branched below eye, extended ventrally and then anteriorly to posteroventral articulation of mandible. Venter with smooth surface; small gular foveae (posterior tentorial pits) originating from shared oval opening, with thin median carina extending from opening anteriorly to mouthparts. Compound eyes prominent, composed of approximately 57 ommatidia. Antenna elongate, length 1.49–1.52 mm, distinct club ( Fig. 68C ) formed by enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–7 each slightly elongate, 8 smallest, slightly elongate, 9 much wider than 8, transverse, 10 ( Fig. 68D ) broader and longer than 9, ventral surface with large basal impression, 11 largest, longer than 9 and 10 combined, with distinct basoventral projection, subbase of projection with round tubercle, apex with tufted setae.

Pronotum ( Fig. 68B ) slightly wider than long, length 0.62 mm, width 0.63–0.64 mm, widest at middle; lateral margins rounded and with small denticles at apical 1/2, convergent basally and sub-parallel at basal 1/4; disc slightly convex, finely punctate, broad median longitudinal sulcus with carinate sides, posteriorly confluent with oval antebasal impression and short mediobasal carina, with pair of discal carinae and lateral longitudinal sulci; with outer pair of antebasal spines and inner pair of angulate tubercles, marginal spines distinct; lateral antebasal foveae small and asetose; with small outer and inner pair of basolateral foveae. Prosternum with anterior part slightly longer than coxal part, with small lateral procoxal foveae; thick hypomeral ridge extending from base to middle of anterior part, with punctiform lateral antebasal hypomeral pit; margin of coxal cavity broadly carinate.

Elytra much wider than long, length 0.77–0.78 mm, width 0.96–0.97 mm; each elytron with three moderately large, asetose basal foveae; long discal stria extending posteriorly from outer basal fovea to approximately apical 1/4 of elytral length; humerus denticulate, subhumeral fovea present, carinate marginal stria extending from fovea to posterior margin of elytron.

Mesoventrite short, demarcated from metaventrite by transverse carinae; median mesoventral foveae narrowly separated, originating from shared opening, large lateral mesoventral foveae not forked internally, with short mesoventral process, with complete marginal stria. Metaventrite prominent admesally, inclined towards middle, with well-developed lateral mesocoxal foveae, two lateral metaventral foveae moving medially and in large, setose shared impression; posterior margin roundly emarginate at middle, with narrow split.

Legs elongate; procoxa with exceptionally long seta at base, protibia with tiny preapical denticle at mesal margin; mesotrochanter ( Fig. 68E ) with distinct ventral spine, mesotibia ( Fig. 68F ) with large blade-like projection before apex; metatrochanter ( Fig. 68G ) with long ventral projection strongly curved at apex, metatibia with long pencil-like apical tuft of setae.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.86–0.92 mm, width 0.87–0.90 mm. Tergite 1 (IV) more than twice as long as 2 (V), lacking basal sulcus, with large mediobasal and one pair of basolateral foveae, with pair of short discal carinae, marginal carinae complete, oblique inner carina thinner than outer one; tergite 2 (V) slightly longer than 3 (VI), 4 (VII) shorter than tergites 2 and 3 combined; tergites 2–4 (V–VII) each with one pair of basolateral foveae, tergite 5 (VIII) semicircular, transverse, posterior margin roundly emarginate at middle. Sternite 2 (IV) with one pair of mediobasal and two pairs of basolateral foveae, with long, oblique lateral carina; midlength of sternites 2–4 (IV–VI) gradually shorter, 5 (VII) slightly longer than 4, 3–5 each with two pairs of small basolateral foveae and short lateral carinae, sternite 6 (VIII) transverse, posterior margin broadly emarginate, sternite 7 (IX) ( Fig. 68H ) weakly sclerotized, slightly oval.

Aedeagus ( Fig. 68I, J ) 0.63 mm long, strongly asymmetric, elongate; median lobe with large extended basal capsule and elongate foramen, ventral stalk in dorsal view broad at middle and abruptly narrowing apically, with deeply forked, weakly sclerotized apex; dorsal lobe large, plate-like, apical part protruding and curved, in lateral view narrowing towards apex; parameres membranous, apically split into two parts.

Female. Similar to male in external morphology; antenna shorter than that for male; antenna and legs lacking modifications; each compound eye composed of approximately 35 ommatidia. Measurements (as for male): body length 2.52–2.53 mm; length/width of head 0.52/ 0.60 mm, pronotum 0.54–0.55/ 0.59–0.60 mm, elytra 0.69– 0.70/ 0.88 mm; abdomen 0.80–0.86/ 0.81 mm; length of antenna 1.15–1.23 mm; genitalia weakly sclerotized ( Fig. 68K ), with elongate, forked lateral sclerites, maximum width 0.41 mm.

Comparative notes. Tribasodites gyirong is placed in the group of species centered on T. antennalis, which share a similar location of the male antennal modifications and the similar aedeagal forms. The male of T. gyirong is morphologically most similar to the sympatric T. pugiunculus by sharing most external characters. It can be readily separated from T. pugiunculus by the larger body size (2.68–2.78 mm vs. 2.30–2.41 mm), presence of a transverse impression on the vertex (lacking in T. pugiunculus ), the relatively longer basal projections of antennomeres 11, and the broadly and deeply split apex of the ventral stalk of the aedeagus.

Distribution. Gyirong County, Tibet, SW China ( Figs 86B , 89 ).

Etymology. This species is named after Gyirong County, where the type locality is situated.

Figures

FIGURE 68. Morphology of Tribasodites gyirong sp. nov. (A–J. Male. K. Female). A. Dorsal habitus. B. Head and pronotum. C. Antennomeres 9–11. D. Antennomere 10, ventral. E. Mesotrochanter. F. Mesotibia. G. Metatrochanter. H. Sternite 7 (IX). I, J. Aedeagus, lateral (I) and ventral (J). K. Genitalia. Scale bars: 0.5 mm in A; 0.3 mm in B, F; 0.2 mm in C, E, G, H–K; 0.1 mm in D.

FIGURE 86. Distribution of Tibetan Batrisini. A. Tribasodites dilophus sp. nov. (circle), T. elongatus sp. nov. (triangle) and T. grandiceps sp. nov. (square). B. T. gyirong sp. nov. (circle), T. kiypu sp. nov. (triangle) and T. mirabilis sp. nov. (square). C. T. prolixicornis sp. nov. (circle), T. Tribasodites pugiunculus sp. nov. (triangle) T. vertexalis sp. nov. (square) and T. yatung sp. nov. (diamond).

FIGURE 89. Environment of and collecting sites at Gyirong Valley. A. General environment of the valley. B–E. Forests (B, E) and collecting sites (C, D) in the valley. D. A sign of Kiypu Village (吉ė村), which is the entrance to the forest. Photo Credit: A by Wen-Xuan Zhang.