Sathytes yigongensis, 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 : 140-142

Sathytes yigongensis sp. nov.

( Figs 61 , 85A , 97A–C )

Chinese common name: ƌŭḛà甲

Type material (13 exx.). HOLOTYPE: CHINA: ♂, ‘ China: Xizang, Nyingchi City, pass nr. Yigong Tea Farm , 30°10’14”N, 94°55’51”E, 2200–2400 m, 11.vii.2021, Peng, Yin & Zhang, Ʊ Ẫffż 波ṁ县ƌŭē厂 ’ ( SNUC) . PARATYPES: CHINA: 3 ♂♂, 4 ♀♀, same data as that of holotype; 1 ♂, 4 ♀♀ , ‘ China: Xizang, Nyingchi City, Pailong Township, Layue Bridge , 29°59’02”N, 94°52’33”E, 2550 m, 13.vii.2021, Peng leg. Ʊ Ẫffż 市ḦË乡Ń 月ss桥 ’ (all paratypes in SNUC) .

Diagnosis. Male. Body length approximately 2.2 mm; ratio (length/width) of head 1.06–1.08, pronotum 1.02– 1.06, elytra 0.79, length of eye/tempus 1.0. Antennomere 9 much wider than long (length/width excluding apophysis 0.80), with hyaline apophysis near apex of mesal margin, antennomere 11 elongate (length/width 1.72), with short protuberance at base, apex of protuberance with tuft of curved setae. Aedeagus broadly rounded at base, slightly bent towards right, apical margin convex at left side. Female. Body length approximately 2.3 mm; antenna lacking modifications, genitalia as in Fig. 61G .

Description. Male. Body ( Fig. 61A ) length 2.18 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short, dense pubescence.

Head ( Fig. 61B ) sub-rectangular at base, slightly longer than wide, length 0.50–0.52 mm, width across eyes 0.47–0.48 mm, length/width 1.06–1.08; vertex weakly raised, with small asetose foveae (dorsal tentorial pits) at level of posterior margin of eyes; frons anteriorly confluent with strongly declining clypeus, weakly impressed medially; clypeus with smooth surface, anterior margin carinate and moderately raised; ocular-mandibular carina short; postgenal region strongly projecting. Venter with small, broadly separated gular foveae (posterior tentorial pits), lacking median carina. Compound eyes moderately prominent, composed of approximately 18 large ommatidia, length of eye/tempus 1.0. Antenna elongate, length 1.13 mm, distinct club ( Fig. 61C ) formed by enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–8 each transverse, 2 slightly wider, 3–8 subequal in width, 9 ( Fig. 61D ) strongly expanded, slightly wider than long, length/width excluding apophysis 0.80, mesal margin moderately oblique, hyaline apophysis located near apex of mesal margin, 10 transverse, length/width 0.62, 11 largest, longer than 9 and 10 combined, length/width 1.72, with short, apically denticulate protuberance at base, apex of protuberance with short, curved tuft of golden setae.

Pronotum ( Fig. 61B ) approximately as long as wide, length 0.51–0.52 mm, width 0.49–0.50 mm, length/width 1.02–1.06, widest at middle; lateral margins rounded, convergent apically and basally; disc weakly convex; asetose lateral antebasal foveae moderately small. Prosternum with anterior part slightly longer than coxal part, with small lateral procoxal foveae; hypomeral ridge absent; margin of coxal cavity moderately carinate.

Elytra much wider than long, length 0.69–0.71 mm, width 0.87–0.90 mm, length/width 0.79; each elytron with four small, asetose basal foveae; lacking discal stria; humerus faintly prominent, subhumeral fovea present, marginal stria extending from fovea to posterior margin of elytron.

Mesoventrite short, demarcated from metaventrite by strongly curved carinae; median mesoventral foveae fused at middle, originating from shared opening, large lateral mesoventral foveae shallowly forked internally, mesoventral process short, with complete marginal stria. Metaventrite weakly prominent admesally, inclined towards middle, with well-developed lateral mesocoxal and two broadly separated lateral metaventral foveae, with large, round median pit shortly anterior to posterior margin, posterior margin broadly emarginate.

Legs elongate, simple.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.57–0.62 mm, width 0.78–0.79 mm. Tergite 1 (IV) more than twice as long as 2 (V), lacking basal sulcus, with one pair of mediobasal and two pairs of basolateral foveae, lacking discal or marginal carina; tergite 2 (V) slightly longer than 3 (VI), 4 (VII) longer than 3 but much shorter than 2 and 3 combined; tergites 2–3 (IV–VI) each with one pair of mediobasal and two pairs of basolateral foveae, 4 with one pair of basolateral foveae and marginal tubercles, tergite 5 (VIII) semicircular, transverse, posterior margin roundly emarginate at middle. Sternite 2 (IV) with one pair of mediobasal and three pairs of basolateral foveae, lateral carina absent; midlength of sternites 2–5 (IV–VII) gradually shorter, sternites 3–4 (IV–VI) each with three pairs and 5 (VII) with one pair of small basolateral foveae, sternite 6 (VIII) transverse, posterior margin broadly emarginate, sternite 7 (IX) ( Fig. 61E ) moderately sclerotized, elongate, apex lacking setae.

Aedeagus ( Fig. 61F ) 0.22 mm long, slightly bent rightwards, plate-like; median lobe with large foramen, apical margin slightly convex at left side.

Female. Similar to male in external morphology; antenna slightly shorter, lacking modifications; each compound eye composed of approximately 15 ommatidia; humeral prominence faint. Measurements (as for male): body length 2.28–2.30 mm; length/width of head 0.50–0.52/ 0.47–0.48 mm, pronotum 0.51/ 0.51–0.52 mm, elytra 0.61–0.63/ 0.86 mm; abdomen 0.73–0.75/ 0.81 mm; length of antenna 1.00– 1.05mm; maximum width of genitalia ( Fig. 61G ) 0.25 mm.

Comparative notes. This species is morphologically most similar to S. panzhaohuii which are sympatric in Yigong, sharing with it a similar body size and an acute apical tubercle of the basal protuberance of antennomeres 11. They can be best separated by the relatively more elongate antennomeres 11, a steeper declining angle of the apicomesal margin of antennomeres 9, and a more anteriorly placed location of the apophysis on this antennomere for S. yigongensis . The new species is also similar to S. pengzhongi and S. proclivis by the oblique mesal margins and apically located apophyses of male antennomeres 9. The male of S. yigongensis can be readily separated by the angulate tubercles at the apices of the basal protuberances of antennomeres 11, different forms of antennomeres 9 and the apophyses on them, as well as the different form of the aedeagus.

Distribution. Bomê County, Tibet, SW China ( Figs 85A , 97A–C ).

Etymology. The new species is named after its type locality, Yigong Township.

Figures

FIGURE 61. Morphology of Sathytes yigongensis sp. nov. (A–F. Male. G. Female). A. Dorsal habitus. B. Head and pronotum. C. Antennomeres 9–11. D. Antennomere 9. E. Sternite 7 (IX). F. Aedeagus, ventral. G. Genitalia. Scale bars: 0.5 mm in A; 0.3 mm in B; 0.2 mm in C; 0.1 mm in D–G.

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 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).