Tribasodites kiypu, 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 : 161-164

Tribasodites kiypu sp. nov.

( Figs 69 , 86B , 88 , 89 )

Chinese common name: 吉âûḃà甲

Type material (9 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) . PARATYPE: CHINA: 4 ♂♂, 4 ♀♀, same data as that of holotype ( SNUC) .

Material not included in type series (5 exx.). 3 ♂♂, 1 ♀, same label data as of type series ( SNUC); 1 ♂, same collectors and also from Gyirong Valley , except ‘pass nr. Ru Kupuqiong, 28°25’47”N, 85°15’50”E, 3000 m, 20.vi.2021, ƱẪU喀NJ吉PWả库âAEṉữ ’ ( SNUC) .

Diagnosis (based on type series). Male. Body length over 2.8 mm. Head sub-rounded at base, slightly narrower than pronotum, tempus long, with rounded posterolateral margin, vertex lacking sulcus, with relatively large, asetose foveae, with distinct mediobasal carina extending from head base anteriorly to slightly posterior to level of anterior margin of eyes, with distinct lateral carina from base to posterior margin of antennal tubercle; antenna elongate, lacking modifications, antennomeres slightly elongate. Pronotum with laterally carinate median and shallow lateral longitudinal sulci, with pair of longitudinal discal carinae composed of spines, with pair of large antebasal and distinct marginal spines. Discal stria of elytron shallow, extending posteriorly to pass half of elytral length; disc finely punctate. Mesotrochanter with blunt ventral spine, mesotibia with elongate spine at apex; metatrochanter with curved projection on ventral margin. Aedeagus elongate, asymmetric; median lobe with large basal capsule and broad foramen, ventral stalk abruptly narrowed and expanded at apex, dorsal lobe broad and flat, paramere membranous. Female. Body length slightly over 2.7 mm, antenna shorter than male, legs lacking spines or projections, genitalia as in Fig. 69H .

Description (based on type series). Male. Body ( Fig. 69A ) length 2.82 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with relatively dense pubescence.

Head ( Fig. 69B ) sub-rounded at base, slightly longer than wide, length 0.60–0.62 mm, width across eyes 0.58– 0.59 mm; vertex with rough surface, lacking sulcus, vertexal foveae (dorsal tentorial pits) asetose, relatively large, mediobasal carina distinct, extending from head base anteriorly to slightly posterior to level of anterior margin of eyes, with pair of sinuate admesal carinae forming inner margins of reversed U-shaped impression that connect vertexal foveae, lateral carina distinct, extending from base to posterior margin of antennal tubercle; posterolateral margin rounded; frons anteriorly demarcated from clypeus by oblique frontal-clypeal ridge, which extended anteriorly for short distance on clypeus, area between moderately raised antennal tubercles weakly impressed; clypeus with rough 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 granulate surface; small gular foveae (posterior tentorial pits) originating from shared oval opening, weak median carina extending from opening anteriorly to mouthparts. Compound eyes prominent, composed of approximately 58 ommatidia. Antenna elongate, length 1.50–1.60 mm, indistinct club formed by slightly enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–8 each slightly elongate, 8 smallest, 9 wider and longer than 8, subconical, 10 shorter than 9, subconical, 11 largest, slightly longer than 9 and 10 combined, subfusiform, impressed dorsally near apex.

Pronotum ( Fig. 69B ) slightly wider than long, length 0.61–0.62 mm, width 0.62–0.64 mm, widest at middle; lateral margins rounded at middle, convergent apically and sub-parallel at basal 1/4; disc slightly convex, finely punctate, median longitudinal sulcus with slightly carinate margins, posteriorly confluent with oval antebasal impression and short mediobasal carina, pair of discal longitudinal carinae ( Fig. 69C ) each composed of four to five distinct spines, with thin lateral longitudinal sulci; with pairs of large antebasal and smaller marginal spines; lateral antebasal foveae small and setose; with small outer and inner pair of basolateral foveae. Prosternum with anterior part slightly longer than coxal part, with small lateral procoxal foveae; distinct hypomeral ridge extending from base to middle of anterior part, lateral antebasal hypomeral pit absent; margin of coxal cavity slightly carinate.

Elytra much wider than long, length 0.77–0.80 mm, width 0.93–0.94 mm; each elytron with three moderately large, asetose basal foveae; discal stria extending posteriorly from outer basal fovea to pass half of elytral length; humerus prominent, 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 broadly separated, originating from shared transverse opening, large lateral mesoventral foveae forked internally, with short, thickened mesoventral process, with complete marginal stria. Metaventrite moderately prominent admesally, inclined towards middle, with well-developed lateral mesocoxal foveae, with two lateral metaventral foveae, posterior margin roundly emarginate and with narrow split at middle.

Legs elongate; procoxa with exceptionally long seta at base; mesotrochanter ( Fig. 69D ) with blunt ventral spine, mesotibia with elongate triangular apical spine; metatrochanter ( Fig. 69E ) with long, curved ventral protuberance.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.84–0.93 mm, width 0.84–0.86 mm. Tergite 1 (IV) approximately 1.3 times as long as 2 (V), lacking basal sulcus, with one pair of mediobasal and two pairs of basolateral foveae, with pair of thin, sub-triangular discal carinae, marginal carinae complete, oblique inner carina thinner than outer one; tergite 2 (V) slightly longer than 3 (VI), 2 and 3 each with two pairs of small basolateral foveae and thin marginal carinae, 4 (VII) shorter than tergites 2 and 3 combined, with one pair of small basolateral foveae and pair of thin marginal carinae; tergite 5 (VIII) semicircular, transverse, posterior margin roundly emarginate at middle. Sternite 2 (IV) with broad setose basal sulcus, with one pair of mediobasal and two pairs of basolateral foveae, lacking lateral carina; midlength of sternites 2–5 (IV–VII) gradually shorter, sternites 3–4 each with broad basal sulcus and three pairs of basolateral foveae, 5 lacking basal sulcus, with one pair of small basolateral foveae, sternite 6 (VIII) transverse, posterior margin broadly emarginate, sternite 7 (IX) ( Fig. 69F, G ) composed of pair of triangular, membranous structures.

Aedeagus ( Fig. 69F, G ) 0.39 mm long, asymmetric, elongate; median lobe with broad basal capsule and large foramen, ventral stalk abruptly narrowed and strongly dilated at apex; dorsal lobe broad and flattened, parameres membranous, apical part weakly sclerotized.

Female. Similar to male in external morphology; antenna shorter than male; legs lacking spines and projections; each compound eye composed of approximately 30 ommatidia. Measurements (as for male): body length 2.77–2.80 mm; length/width of head 0.60–0.61/ 0.57–0.58 mm, pronotum 0.61–0.62/ 0.61–0.63 mm, elytra 0.72–0.77/ 0.91– 0.92 mm; abdomen 0.87–0.88/ 0.87–0.88 mm; length of antenna 1.43–1.47 mm; genitalia weakly sclerotized ( Fig. 69H ), with broad lateral arms, maximum width 0.31 mm.

Comparative notes. This species is allied with T. dilophus , T. mirabilis and T. yatung , all described in this paper, in sharing relatively elongate habitus and postocular margins, and having simple male antennae. The male of Tribasodites kiypu can be readily separated from the other three species by the much larger body size (2.82 mm (2.52–2.65 mm for none-type specimens) vs. 2.14–2.15 mm for T. dilophus , 2.06 mm for T. mirabilis and 1.97–2.13 mm for T. yatung ), and by the unique form of the aedeagus; from T. mirabilis also by the simple hind legs, which are strongly modified in the latter species.

Distribution. Gyirong County, Tibet, SW China ( Figs 69 , 86B , 88 , 89 ).

Etymology. The specific epithet refers to Kiypu (= Ji Fu) Village, type locality of this species.

Comments on none-type material. Three males and one female from the type locality, and one male from a nearby collecting site have the aedeagi identical to that of the holotype. They differ from the type series by the smaller body size, a slightly lighter body color, a smoother surface of the head dorsum, the U-shaped sulcus of the vertex not being ridged at its inner margins, the lack of an oblique frontal-clypeal ridge, and a thinner and shallower median sulcus of the pronotum. Note is that the pronotal spines, and spines/projections of the legs are, however, of same shapes as the type series. Such differences among the population from a same collecting site is not commonly detected for batrisines, these differences are temporarily considered as intraspecific variation within T. kiypu .

The measurements of these ‘smaller-form’ individuals are given here for comparative purposes: 3 males from the type locality: each compound eye composed of approximately 45 ommatidia; body length 2.52–2.53 mm, length/ width of head 0.53–0.55/ 0.54 mm, pronotum 0.57–0.59/ 0.57–0.58 mm, elytra 0.76–0.77/ 0.88 mm; abdomen 0.73– 0.75/ 0.77 mm; length of antenna 1.41–1.43 mm; 1 female from the type locality: each compound eye composed of approximately 25 ommatidia; body length 2.56 mm, length/width of head 0.54/ 0.53 mm, pronotum 0.56/ 0.55 mm, elytra 0.70/ 0.81 mm; abdomen 0.79/ 0.75 mm; length of antenna 1.26 mm; 1 male from Ru Kupuqiong: each compound eye composed of approximately 48 ommatidia; body length 2.65 mm, length/width of head 0.55/ 0.54 mm, pronotum 0.58/ 0.59 mm, elytra 0.76/ 0.89 mm; abdomen 0.74/ 0.80 mm; length of antenna 1.43 mm.

Figures

FIGURE 69. Morphology of Tribasodites kiypu sp. nov. (A–G. Male. H. Female). A. Dorsal habitus. B. Head and pronotum. C. Pronotum, in dorsolateral view. D. Mesotrochanter. E. Metatrochanter. F, G. Aedeagus, ventral (F) and lateral (G). H. Genitalia. Scale bars: 0.5 mm in A; 0.3 mm in B; 0.2 mm in C; 0.1 mm in D–H.

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 88. Environment of and collecting sites at Gyirong Valley (吉P沟). A. General environment of Ru Kupuqiong. B. Collecting site at Ru Kupuqiong (ả库âAE). C. A stone by the path at Ru Kupuqiong, under which two larvae (D) and an adult (E) of Hingstoniella lata Jeannel were spotted. Photo Credit: A, D, E by Wen-Xuan Zhang.

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.