Sathytes pseudograndis, 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 : 131-133

Sathytes pseudograndis sp. nov.

( Figs 57 , 84B , 93F, G )

Chinese common name: 伪ũḛà甲

Type material (8 exx.). HOLOTYPE: CHINA: ♂ , ‘ China: Xizang, Dinggyê County, Zhêntang Town, Ganma Zangbo Valley , 27°51’50”N, 87°24’24”E, 2400 m, 28.vi.2021, Z. Peng leg., ƱẪŤĠ县ĿƋWH玛Ẫ布河ě ’ ( SNUC) . PARATYPES: CHINA: 2 ♂♂, 5 ♀♀, same data as that of holotype ( SNUC) .

Diagnosis. Male. Body length greater than 2.8 mm; ratio (length/width) of head 1.09–1.14, pronotum 1.03– 1.08, elytra 0.84–0.86, length of eye/tempus 0.95. Antennomere 9 approximately as long as wide (length/width excluding apophysis 1.04), with hyaline apophysis at middle of mesal margin, antennomere 11 elongate (length/width 1.56), with short protuberance at base, apex of protuberance with tuft of curved setae. Aedeagus broad throughout length, slightly bent leftwards, with apical margin slightly emarginate. Female. Body length approximately 3.0 mm; antenna lacking modifications, genitalia as in Fig. 57G .

Description. Male. Body ( Fig. 57A ) length 2.80–2.97 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 57B ) sub-rectangular at base, slightly longer than wide, length 0.61–0.63 mm, width across eyes 0.55–0.56 mm, length/width 1.11–1.12; vertex moderately raised, with small asetose foveae (dorsal tentorial pits) located posterior to level of posterior margin of eyes; frons anteriorly confluent with strongly declining clypeus, flat; 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 distinct median carina or sulcus. Compound eyes prominent, composed of approximately 20 large ommatidia, length of eye/tempus 0.95. Antenna elongate, length 1.39–1.46 mm, distinct club ( Fig. 57C ) formed by enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–7 each transverse, subequal in width, 8 slightly narrower and shorter than 7, 9 ( Fig. 57D ) strongly enlarged, approximately as long as wide, length/width excluding apophysis 1.04, mesal margin moderately expanded at middle, hyaline apophysis located at middle of mesal margin, 10 transverse, length/width 0.67, 11 largest, as long as 9 and 10 combined, length/width 1.56, with small protuberance at base, apex of protuberance with curved tuft of golden setae.

Pronotum ( Fig. 57B ) approximately as long as wide, length 0.66–0.69 mm, width 0.64 mm, length/width 1.03– 1.08, widest at middle; lateral margins rounded, convergent apically and basally; disc weakly convex; asetose lateral antebasal foveae distinct. 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 0.89–0.90 mm, width 1.04–1.06 mm, length/width 0.85; each elytron with four large, asetose basal foveae; lacking discal stria; humerus slightly angulate, 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 contiguous, originating from shared oval opening, large lateral mesoventral foveae forked internally, mesoventral process short, with complete marginal stria. Metaventrite moderately prominent admesally, weakly inclined towards middle, with well-developed lateral mesocoxal and two lateral metaventral foveae, with large, round median pit shortly anterior to posterior margin, posterior margin broadly emarginate at middle, lacking split.

Legs elongate, simple.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.80–0.91 mm, width 0.94–0.95 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 carina, marginal carina thin and short, faint; 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. Sternites depressed along 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. 57E ) moderately sclerotized, elongate, apex asetose.

Aedeagus ( Fig. 57F ) 0.37 mm long, slightly asymmetric and bent leftwards, plate-like; median lobe with large foramen, broadened throughout entire length, with apex slightly wider than base, apical margin slightly emarginate.

Female. Similar to male in external morphology; antenna slightly shorter, lacking modifications; each compound eye composed of approximately 14 ommatidia; humerus weakly prominent. Measurements (as for male): body length 2.91–3.05 mm; length/width of head 0.61–0.63/ 0.57–0.58 mm, pronotum 0.66–0.67/ 0.65 mm, elytra 0.84–0.86/ 1.07–1.08 mm; abdomen 0.93–0.95/0.99–1.00 mm; length of antenna 1.30–1.41 mm; maximum width of genitalia ( Fig. 57G ) 0.29 mm.

Comparative notes. This species is closely related to S. grandis Löbl, 1979 by sharing a similar body size, the position and form of the apophyses of antennomeres 9 and basal projection of antennomeres 11, and the form of the aedeagus. It differs from S. grandis by the relatively smaller eyes (ratio of eye/tempus 0.95 vs.> 1.1 in S. grandis ), and relatively markedly smaller antennomeres 9 in relation to 8 and 10. Sathytes pseudograndis is also similar to S. xizangensis by the similar male antennal structures, but can be separated from it by the much larger body size (2.80–2.97 mm vs. 2.53–2.73 mm), the more strongly inclined anteromesal margins of antennomere 9, and the much smaller basal projections of antennomeres 11.

Distribution. Dinggyê County, Tibet, SW China ( Figs 84B , 93F, G ).

Etymology. The specific epithet is a combination of the prefix pseudo - (false, fake)’ and ‘ grandis (large, great)’, indicating the morphological similarity of this species to S. grandis .

Figures

FIGURE 57. Morphology of Sathytes pseudograndis 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, C; 0.1 mm in D–G.

FIGURE 84. Distribution of Tibetan Batrisini. A. Sathytes magnus Yin & Li (circle), S. panzhaohuii Yin & Shen (triangle) and S. pengzhongi sp. nov. (square). B. S. proclivis sp. nov. (circle), S. pseudograndis sp. nov. (triangle) and S. simplex Löbl (square). C. S. sympatricus sp. nov. (circle), S. transversus Yin & Shen (triangle) and S. virupaksa sp. nov. (square).

FIGURE 93. Environment of and collecting sites at Zhêntang Valley (ĿƋ沟). Slopes at altitudes of 3700 m (A), 4000 m (B), and 3050 m (C). D. Nadang Village (Ḅ当村). E. Road to Xiuxiongma Village (šŏ玛村). F, G. Environment of Ganma Zangbo Valley (HḼẪ布河ě). Photo Credit: F, G by Zhong Peng.