Batrisiella curvitibialis, 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 : 80-83

Batrisiella curvitibialis sp. nov.

( Figs 34 , 80C , 97C , 99B, C )

Chinese common name: DZḇ小毛唇à甲

Type material ( 9 exx.). HOLOTYPE: CHINA: ♂, ‘ China: Xizang, Mêdog County, Beibeng , road to Gelin Vill., 29°14’49.15”N, 95°11’2.86”E, 1060 m, 2019.vii.23; leaf litter, Z.-W. Yin leg., [ƱẪÜ崩乡格ff村]’ ( SNUC).

PARATYPES: CHINA: 1 ♂, 2 ♀♀, same data as that of holotype ; 1 ♂, China: Xizang, Mêdog County, nr. Yarang Power Station , 29°15’44.28”N, 95°14’44.63”E, 885 m, 2019.vii.24, leaf litter, Z.-W. Yin leg., [ƱẪẸṘ亚üΨ ‖] ; 3 ♂♂, China : Tibet, Mêdog County, 80K (ca. 29°39’24”N, 95°29’21”E), 2111 m, 11.viii.2016, Chen Zhi-Lin leg. ; 1 ♂, China: Nyingchi County, Pailong Country , 30°0’34.71”N, 94°57’57.64”E, 2190 m, 2019.vii.15–viii.04, FIT, Z.-W. Yin leg., [ƱẪffżḦËƖǎ]’ (all paratypes in SNUC) .

Diagnosis. Male. Body length 2.02–2.06 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 apical 5/6 of elytral length. Legs with mesotibia with small apical tubercle, metafemur protuberant on ventral margin and at apex, metatibia sinuate at base. Admesal area of posterior part of metaventrite densely setose. Surface of tergite 4 (VII) broadly and transversely impressed, with pair of small, oval cavities at middle. Aedeagus strongly asymmetric; median lobe with large basal capsule and short basoventral projection, ventral stalk curved ventrally; dorsal lobe transverse at base and strongly curved, apex split into two lobes; parameres reduced to round, membranous structure. Female. Body length 1.92 mm; antenna shorter, metaventrite, legs and abdomen lacking modifications, genitalia as in Fig. 6K .

Description. Male. Body ( Fig. 34A ) length 2.02–2.06 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 34B ) sub-rectangular at base, slightly broader than long, length 0.41–0.42 mm, width across eyes 0.44–0.45 mm; vertex finely punctate, with moderately large, asetose vertexal foveae (dorsal tentorial pits), lacking U-shaped sulcus connecting foveae, with thin mediobasal carina extending from subbase to level of anterior margins of vertexal foveae, with V-shaped sulcus between antennal tubercles; antennal tubercles moderately raised; frons slightly impressed medially, confluent with clypeus at middle and carinate anterolaterally; clypeus with smooth surface, its anterior margin carinate and moderately raised; ocular-mandibular carina complete. Venter with single, small gular fovea (posterior tentorial pit), with thin median carina extending from fovea anteriorly to mouthparts. Compound eyes prominent, composed of approximately 30 ommatidia. Antenna moderately elongate, length 1.08 mm, apical three antennomeres forming indistinct club; antennomere 1 thick, subcylindrical, apicolateral portion with small inner glandular structure, lacking trichome, 2–8 each elongate, 8 smallest, 9 much larger than 8, 10 as long as and slightly broader than 9, 11 largest, as long as 9 and 10 combined, slightly oval.

Pronotum ( Fig. 34B ) approximately as long as broad, length 0.43–0.44 mm, width 0.45–0.46 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; 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 0.61–0.62 mm, width 0.76–0.78 mm; each elytron with two large, asetose basal foveae, lacking subbasal fovea; discal stria extending from outer basal fovea to apical 5/6 of elytral length; humerus angulate, subhumeral fovea absent, sulcate marginal stria extending from where fovea supposed to be 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 broadly impressed at middle, with large, setose lateral mesocoxal foveae and pair of smaller, setose lateral metaventral foveae; admesal area ( Fig. 34C ) densely setose at posterior half; posterior margin with small and narrow split at middle.

Legs elongate; mesotibia ( Fig. 34D ) with small apical tubercle; metafemur ( Fig. 34E ) projecting on ventral margin at apical 1/3, apex strongly extended on ventral side such that femoral-trochanteral joint is covered, metatibia ( Fig. 34F ) thin and sinuate at basal 1/3.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.69–0.71 mm, width 0.58–0.61 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; tergites 2–4 (V–VII) tightly compressed, each with one pair of basolateral foveae, tergite 4 (VII) ( Fig. 34G ) slightly shorter than 2 and 3 combined along middle, with pair of small, oval cavities at middle, surface with broad and transverse median impression, tergite 5 (VIII) broad and slightly transverse, posterior margin roundly emarginate at middle. Sternite 2 (IV) with large mediobasal and pair of broad, setose basolateral sockets, with short lateral and long, complete marginal carinae, midlength approximately as long as 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. 34H ) asymmetric, transversely slightly oval, weakly sclerotized.

Aedeagus ( Fig. 34I, J ) 0.33 mm long, strongly asymmetric; median lobe with large basal capsule and sub-triangular foramen, ventral stalk narrowing towards apex; dorsal lobe transverse, strongly curved, broad throughout whole length, apex split into two unequal lobes; parameres reduced to single round membranous structure.

Female. Similar to male in external morphology; antenna shorter; each compound eye composed of approximately 22 ommatidia; humerus weakly prominent; metaventrite lacking densely setose area, legs lacking tubercles or projections; abdomen lacking modifications. Measurements (as for male): body length 1.96 mm; length/width of head 0.40–0.41/ 0.41 mm, pronotum 0.42–0.43/ 0.42–0.45 mm, elytra 0.52–0.54/ 0.69–0.74 mm; abdomen 0.61– 0.66/ 0.66–0.68 mm; length of antenna 0.95–0.98 mm; maximum width of genitalia ( Fig. 34K ) 0.25 mm.

Comparative notes. The new species is morphologically distinct and can be readily separated from all known congeners by the conspicuously modified hindlegs, as well as the form of the modification of male tergite VII. Females from the same locality may be identified by the shape of the genitalia without association with the male.

Distribution. Mêdog County, Tibet, SW China ( Figs 80C , 97C , 99B, C ).

Etymology. The specific epithet is combined from ‘ curvus, - a, - um ’ (bent, curved) and ‘ tibalis, - le ’ (tibial), referring to the sinuate male metatibia of the new species.

Figures

FIGURE 6. Morphology of Arthromelodes championi (Jeannel) comb. nov. (A–G. Male. H. Female). A. Dorsal habitus. B. Head and pronotum. C. Antennomeres 7–11. D. Mesotibia. E. Sternite 7 (IX). F, G. Aedeagus, lateral (F) and ventral (G). H. Genitalia. Scale bars: 0.5 mm in A; 0.3 mm in B; 0.2 mm in C, D, F, G; 0.1 mm in E, H.

FIGURE 34. Morphology of Batrisiella curvitibialis sp. nov. (A–J. Male. K. Female). A. Dorsal habitus. B. Head and pronotum. C. Metaventrite. D. Mesotibia. E. Metafemur. F. Metatibia. G. Tergite 4 (VII). H. Sternite 7 (IX). I, J. Aedeagus, anterior (I) and lateral (J). K. Genitalia. Scale bars: 0.5 mm in A; 0.2 mm in C–G; 0.05 mm in H; 0.1 mm in I–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 97. Environment of and collecting sites at Nyingchi area. A. Sign of Yigong Tea Farm (ƌŭē厂). B. Forest near Yigong. C. Forest at Pailong Township (ḦË乡). D. Forest near Tongmai Town (ȃ9W).

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.