Batrisodes guoguotang, 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 : 90-92

Batrisodes guoguotang sp. nov.

( Figs 38 , 81A , 99D, G )

Chinese common name: 果果Ƌqà甲

Type material ( 1 ex.). HOLOTYPE: CHINA: ♂, ‘ China: Xizang, Mêdog County, forest nr. Guoguotang Great Bend , 29°18’39.35”N, 95°16’25.75”E, 1180 m; 2019.vii.22, leaf litter, Z.-W. Yin leg. [ƱẪẸṘ果果ḙ]’ ( SNUC).

Diagnosis. Male. Body length 2.37 mm. Head sub-rectangular at base, approximately as broad as pronotum; head and antenna lacking modifications. Pronotum with five dorsally visible longitudinal sulci, discal sulci strongly curved at middle, one pair of marginal sulci present ventral to lateral expansion. Elytron with short discal stria. Mesofemur and mesotibia simple; metatrochanter with large ventral projection, metatibia with blunt apical projection and long bunch of setae at apex. Aedeagus strongly asymmetric; median lobe with large basal capsule and foramen, dorsal lobe well-developed, with narrowed apex deeply forked, split to three lobes.

Description. Male. Body ( Fig. 38A ) length 2.37 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with relatively dense pubescence.

Head ( Fig. 38B ) sub-rectangular at base, slight wider than long, length 0.52 mm, width across eyes 0.55 mm; vertex finely punctate, with large, asetose vertexal foveae (dorsal tentorial pits), with U-shaped sulcus connecting foveae, with sparse large punctures along outer margin of sulcus, lateral vertexal carina faint, extending from occipital constriction to level of middle of eyes, mediobasal carina as long as lateral ones; antennal tubercles moderately raised; frons impressed at middle, confluent with clypeus; clypeus with rough surface, its entire anterior margin carinate and raised; ocular-mandibular carina indistinct. Venter with granulate surface; small gular foveae (posterior tentorial pits) originating from shared opening, with distinct median carina extending from opening anteriorly to mouthparts. Compound eyes prominent, composed of approximately 20 large ommatidia. Antenna lacking distinct club and modification, length 1.24 mm; antennomere 1 thick, subcylindrical, 2–7 each elongate, gradually shorter, 8 smallest, 9 much larger than 8, 10 slightly broader than 9, 11 largest, as long as 9 and 10 combined, subconical.

Pronotum ( Fig. 38B ) approximately as long as wide, length 0.50 mm, width 0.53 mm, widest at middle; lateral margins rounded; disc slightly convex, finely punctate, antebasal tubercles small, lacking discal spines, with one median, one pair of discal and one pair of lateral longitudinal sulci, discal sulci strongly curved at middle; with one pair of marginal sulci beneath lateral expansions; with small asetose median pit and large, setose lateral antebasal foveae; outer and inner pair of basolateral foveae distinct. Prosternum with anterior part slightly longer than coxal part, well-demarcated from hypomera by pair of lateral carinae, which extend posterolaterally to form complete hypomeral ridges; lateral procoxal foveae small; anterior and lateral margin of coxal cavity carinate.

Elytra wider than long, length 0.69 mm, width 0.86 mm; each elytron with three large, asetose basal foveae, inner two close; discal stria only broadly and shallowly present for short distance posterior to outer basal fovea; small subhumeral fovea present, with carinate marginal stria extending from fovea to posterior margin of elytron.

Mesoventrite short, demarcated from metaventrite by thin carinae; median mesoventral foveae narrowly separated, lateral mesoventral foveae deeply forked internally. Metaventrite moderately impressed at middle, with welldeveloped lateral mesocoxal and two lateral metaventral foveae, posterior margin with small and narrow split at middle.

Legs more or less robust, lacking distinct modifications except for metatrochanter. Pro- and mesotrochanter each with tiny tubercle on ventral margin, pro- and mesotibia with small apical denticle; metatrochanter ( Fig. 38C ) with large, curved ventral projection, metatibia ( Fig. 38D ) with dense golden setae along mesal margin of apical 1/2, apex with small, blunt projection and elongate bunch of long setae.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.68 mm, width 0.79 mm. Tergite 1 (IV) approximately twice as long as 2 (V), with pair of short, triangular discal carinae, basal sulcus separated by one pair of mediobasal and two pairs of basolateral foveae, with thick marginal carinae; tergite 2 (V) slightly longer than 3 (VI), 4 (VII) as long as 2 and 3 combined, with pair of small tubercles at lateral margins; tergites 2–4 (V–VII) each with one pair of basolateral foveae, tergite 5 (VIII) semicircular. Sternite 2 (IV) with one pair of small mediobasal and three pairs of basolateral foveae; midlength of sternites 2–5 (IV–VII) gradually shorter, 3–5 each with one pair of small basolateral foveae, sternite 6 (VIII) transverse, posterior margin broadly impressed, sternite 7 (IX) ( Fig. 38E ) with asymmetric, membranous basal part and semicircular, well-sclerotized apical part.

Aedeagus ( Fig. 38F, G ) 0.52 mm long, strongly asymmetric; median lobe with large basal capsule and foramen, basoventral projection short, ventral stalk with two long preapical setae; dorsal lobe well-developed, apically narrowed and deeply forked.

Female. Unknown.

Comparative notes. Batrisodes guoguotang is apparently allied with B. hanmi by sharing most external characters, as well as a similar form of the aedeagus. The new species may be separated from B. hanmi by the following characters: 1) more strongly curved discal longitudinal sulci of the pronotum, 2) a smaller ventral denticle of the mesotrochanter (much larger ventral spine in B. hanmi ), 3) a large projection on the ventral margin of the metatrochanter (small tubercle in B. hanmi ), and 4) the apical portion of the aedeagal dorsal lobe split into with three lobes (split into two lobes in B. hanmi ).

Distribution. Mêdog County, Tibet, SW China ( Figs 81A , 99D, G ).

Etymology. The new species is named after the Guoguotang Great Bend of Yarlung Tsangpo Grand Canyon located near Mêdog County.

Figures

FIGURE 38. Morphology of Batrisodes guoguotang sp. nov., male. A. Dorsal habitus. B. Head and pronotum. C. Metatrochanter and metafemur. D. Metatibia. E. Sternite 7 (IX). F, G. Aedeagus, lateral (F) and ventral (G). Scale bars: 0.5 mm in A; 0.3 mm in B–D; 0.1 mm in E; 0.2 mm in F, G.

FIGURE 81. Distribution of Tibetan Batrisini. A. Batrisodes guoguotang sp. nov. (circle) and B. hanmi sp. nov. (triangle). B. Coryphomimus levigatus sp. nov. C. Coryphomodes budda sp. nov. (circle), C. cephalicus sp. nov. (triangle) and C. chenzhilini 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.