Tribasodites bari, 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 : 144-147

Tribasodites bari sp. nov.

( Figs 62 , 85C , 99F )

Chinese common name: 巴Uûḃà甲

Type material (10 exx.). HOLOTYPE: CHINA: ♂ , ‘ China: Mêdog County, pass from Bari Village to Renqingbeng Temple, 29°18’45”N, 95°21’27”E, ca. 1830 m, 19.iii.2017, X.-B. Song leg. [ƱẪẸṘ县巴U村 -仁ů崩寺]’ ( SNUC) . PARATYPES: CHINA: 4 ♂♂, 5 ♀♀, same data as that of holotype ( SNUC) .

Diagnosis. Male. Body length approximately 2.0 mm. Head sub-rectangular at base, narrower than pronotum, tempus moderately short, denticulate at posterolateral angle, vertex lacking sulcus, with relatively large, asetose foveae, with thin, short mediobasal carina extending from head base anteriorly beyond level of anterior margin of eyes, with distinct lateral carina from base to posterior margin of antennal tubercle; antenna elongate, with modified antennomeres 9–11, antennomere 11 with long basal projection extended posteriorly from mesal margin of basal cavity. Pronotum with laterally carinate median and lateral longitudinal sulci, with pair of discal carinae, with small antebasal and much larger marginal spines. Discal stria of elytron shallow, extending posteriorly to basal 3/5 of elytral length; disc with relatively large and shallow punctures. Protibia with small preapical denticle, protrochanter with tiny ventral tubercle; mesotibia with distinct apical spine; metatrochanter with large projection on ventral margin, mesal margin of metatibia with row of dense golden setae along apical 2/5. Aedeagus strongly asymmetric; median lobe with elongate basal capsule and foramen, ventral stalk broad at middle and then strongly narrowing apically, dorsal lobe large, plate-like, protruding apically and with numerous spine-like structures at apex. Female. Body length approximately 2.0 mm; antenna lacking modifications, legs lacking spine, tubercle, or projection, genitalia as in Fig. 62H .

Description. Male. Body ( Fig. 62A ) length 1.96–1.98 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with relatively dense pubescence.

Head ( Fig. 62B ) sub-rectangular at base, much wider than long, length 0.36–0.37 mm, width across eyes 0.45– 0.46 mm; vertex smooth, lacking sulcus, vertexal foveae (dorsal tentorial pits) asetose, relatively large, mediobasal carina thin, extending from head base anteriorly to beyond level of anterior margin of eyes, lateral carina distinct, extending from base to posterior margin of antennal tubercle; posterolateral angle angulate; frons anteriorly demarcated from clypeus by frontal-clypeal ridge, weakly impressed between large, moderately raised antennal tubercles; clypeus with smooth surface, its entire anterior margin carinate and moderately raised; ocular-mandibular carina complete, distinct. Venter with smooth surface; small gular foveae (posterior tentorial pits) originating from shared round opening, with faint median carina extending from opening anteriorly to mouthparts. Compound eyes prominent, composed of approximately 45 ommatidia. Antenna elongate, length 1.10–1.13 mm, distinct club ( Fig. 62C ) formed by enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–7 each slightly elongate, 8 smallest, 9 much wider than 8, asymmetric, 10 much broader and longer than 9, anterior margin inclined, ventral surface with broad impression at base, 11 largest, longer than 9 and 10 combined, constricted at basal 1/3, large basal projection extended posteriorly from mesal margin of deep basal cavity.

Pronotum ( Fig. 62B ) wider than long, length 0.45 mm, width 0.50–0.51 mm, widest at middle; lateral margins rounded at apical 1/2, convergent basally and parallel at basal 1/3; disc slightly convex, finely punctate, 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 small antebasal and much larger marginal spines; 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; thin hypomeral ridge extending from base to middle of anterior part, with punctiform lateral antebasal hypomeral pit; margin of coxal cavity weakly carinate.

Elytra wider than long, length 0.61–0.62 mm, width 0.72–0.74 mm; each elytron with three moderately large, asetose basal foveae; shallow discal stria extending posteriorly from outer basal fovea to basal 3/5 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 forked internally, with short mesoventral process, marginal stria complete. Metaventrite prominent admesally, inclined towards middle, with well-developed lateral mesocoxal and two lateral metaventral foveae, posterior margin with small and narrow split at middle.

Legs elongate; protrochanter with small ventral spine, protibia with small preapical denticle at mesal margin; mesotibia with short but distinct spine at apex; metatrochanter ( Fig. 62D ) with large ventral projection, metatibia with dense golden setae along mesal margin from basal 3/5 to apex.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.54–0.55 mm, width 0.65–0.68 mm. Tergite 1 (IV) more than twice as long as 2 (V), thin basal sulcus separated by widely separated mediobasal and one pair of large basolateral foveae, inner marginal carina oblique, complete, outer one much thicker, complete; 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 short lateral carina; midlength of sternites 2–4 (IV–VI) gradually shorter, 5 (VII) slightly longer than 4, 3–5 each with one pair of small basolateral foveae, sternite 6 (VIII) transverse, posterior margin broadly emarginate, sternite 7 (IX) ( Fig. 62E ) weakly sclerotized, slightly oval.

Aedeagus ( Fig. 62F, G ) 0.44 mm long, strongly asymmetric, elongate; median lobe with elongate basal capsule and foramen, ventral stalk in dorsal view broad at middle, narrowing towards apex; dorsal lobe large, plate-like, apical part protruding and curved, with numerous spine-like structures at apex; parameres membranous, apically split into two parts.

Female. Similar to male in external morphology; antenna slightly shorter, lacking modifications, legs lacking tubercle, spine or projection; each compound eye composed of approximately 40 ommatidia; humerus slightly denticulate. Measurements (as for male): body length 1.98–2.09 mm; length/width of head 0.38–0.42/ 0.47–0.51 mm, pronotum 0.45–0.47/ 0.53 mm, elytra 0.60–0.62/ 0.74–0.79 mm; abdomen 0.56–0.61/ 0.67–0.71 mm; length of antenna 1.00 mm; maximum width of genitalia ( Fig. 62H ) 0.19 mm.

Comparative notes. Tribasodites bari is apparently close to T. antennalis Jeannel from northern India, which is the type species of the genus, by the similar form of the male antennal modifications and a similar general form of the aedeagus. They can be separated by the denticulate posterolateral angles of the head (rounded in T. antennalis), a much broader mesal margin of antennomere 10 (roundly truncate in T. bari , anterior and posterior margin inclined and mesally forming an acute apex in T. antennalis), and a much longer basal projection of antennomere 11. The new species also shares with T. pugiunculus a similar appearance of the head, pronotum and elytra, but can be separated from this species by the different structure of the antennal modifications and the aedeagus, and much smaller apical spines of the male mesotibiae. The denticulate posterolateral angles of the head of T. bari similarly occur in the Japanese T. picticornis Nomura (1986: fig. 1), but otherwise these two species can be distinguished by the different form of the male antennae and the aedeagus, as well as by their distributions.

Distribution. Mêdog County, Tibet, SW China ( Figs 85C , 99F ).

Etymology. The new species is named after its type locality, i. e., Bari Village.

Remarks. One male specimen was found with parasitic Laboulbeniales on the anterior margin of right femur ( Fig. 62I ) and on the lateral margin of right tibia.

Figures

FIGURE 62. Morphology of Tribasodites bari sp. nov. (A–G, I. Male. H. Female). A. Dorsal habitus. B. Head and pronotum. C. Antennomeres 9–11. D. Metatrochanter. E. Sternite 7 (IX). F, G. Aedeagus, lateral (F) and ventral (G). H. Genitalia. I. Laboulbeniales on right femur. Scale bars: 0.5 mm in A; 0.3 mm in B; 0.2 mm in C, F, G; 0.1 mm in D; 0.05 mm in E, H, I.

FIGURE 85. Distribution of Tibetan Batrisini. A. Sathytes xizangensis Yin & Shen (circle) and S. yigongensis sp. nov. (cross). B. Tangius glabellus Yin & Li. C. Tribasodites bari sp. nov. (circle), T. cellulanus sp. nov. (triangle) and T. constrictus sp. nov. (square).

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.