Sathytes caichenyangi, 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 : 118-120

Sathytes caichenyangi sp. nov.

( Figs 51 , 83B , 95A, B )

Chinese common name: Ḛ氏ḛà甲

Type material (2 exx.). HOLOTYPE: CHINA: ♂ , ‘ China: Xizang, Cona County, Lebu Valley , pass to Mama Vill., 27°50’16”N, 91°45’48”E, 2400–2700 m, 04.vii.2021, Z. Peng, Z. Yin & W. Zhang leg., ƱẪDZḄ县勒布沟Þ玛 乡 ’ ( SNUC) . PARATYPE: CHINA: 1 ♀, same data as that of holotype ( SNUC) .

Diagnosis. Male. Body length approximately 3.5 mm; ratio (length/width) of head 1.13, pronotum 1.07, elytra 0.84, length of eye/tempus 0.78. Antennomere 9 as long as wide (length/width excluding apophysis 1.0), with hyaline apophysis posterior to middle of mesal margin, antennomere 11 elongate (length/width 1.70), with moderately long protuberance at base, apex of protuberance with tuft of curved setae. Aedeagus broad throughout length, with rounded apical margin. Female. Body length approximately 3.6 mm; antenna lacking modifications, genitalia as in Fig. 51G .

Description. Male. Body ( Fig. 51A ) length 3.48 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 51B ) sub-rectangular at base, slightly longer than wide, length 0.71 mm, width across eyes 0.63 mm, length/width 1.13; 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 28 large ommatidia, length of eye/tempus 0.78. Antenna elongate, length 1.71 mm, distinct club ( Fig. 51C ) 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. 51D ) strongly enlarged, as long as wide, length/width excluding apophysis 1.0, mesal margin moderately expanded at middle, hyaline apophysis located slightly posterior to middle of mesal margin, 10 transverse, length/ width 0.77, 11 largest, approximately as long as 9 and 10 combined, length/width 1.70, with small protuberance at base, apex of protuberance with curved tuft of golden setae.

Pronotum ( Fig. 51B ) approximately as long as wide, length 0.76 mm, width 0.71 mm, length/width 1.07, 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 1.07 mm, width 1.27 mm, length/width 0.84; each elytron with four large, asetose basal foveae; discal stria shallow and short; humerus weakly 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, large lateral mesoventral foveae forked internally, mesoventral process short. 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, with thin marginal carina.

Legs elongate, simple.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.95 mm, width 1.15 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 and 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. 51E ) moderately sclerotized, elongate, apex with few long setae.

Aedeagus ( Fig. 51F ) 0.36 mm long, slightly asymmetric and bent leftwards, plate-like; median lobe with large foramen, broadened throughout entire length, with apex approximately as wide as base, apical margin evenly rounded.

Female. Similar to male in external morphology; antenna slightly shorter, lacking modifications; each compound eye composed of approximately 13 ommatidia; humerus faintly prominent. Measurements (as for male): body length 3.62 mm; length/width of head 0.77/ 0.63 mm, pronotum 0.81/ 0.74 mm, elytra 1.04/ 1.28 mm; abdomen 1.10/ 1.23 mm; length of antenna 1.74 mm; maximum width of genitalia ( Fig. 51G ) 0.32 mm.

Comparative notes. This species is allied with S. grandis Löbl distributed in central Nepal and S. pseudograndis by sharing similar forms of male antennomeres 9 and 11, and a large body size. The male of Sathytes caichenyangi differs from S. grandis in the much larger body size (3.5 mm vs. 3.0 mm), the relatively much smaller antennomeres 9 in relation to the head size, and a much longer basal protuberance of antennomeres 11; from S. pseudograndis by the much larger size (3.5 mm vs. 2.80–3.0 mm), much longer postocular margins in relation to eye length (0.78 vs 0.95), the more posterior position of the hyaline apophysis of antennomeres 9, the much longer basal protuberance of antennomeres 11, and the narrower apex of the aedeagus.

Distribution. Cona County, Tibet, SW China ( Figs 83B , 95A, B ).

Etymology. This species is named after Chenyang Cai (ḚṚŖ) for his various support and help during my work on the Tibetan pselaphine fauna.

Figures

FIGURE 51. Morphology of Sathytes caichenyangi 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 83. Distribution of Tibetan Batrisini. A. Sathytes aequalis sp. nov. (circle), S. alpicola Yin & Shen (triangle) and S. asura sp. nov. (square). B. S. caichenyangi sp. nov. (circle), S. chayuensis Yin & Shen (triangle) and S. dawai sp. nov. (square). C. S. duojii sp. nov. (circle), S. laticornis sp. nov. (triangle) and S. linzhiensis Yin & Shen (square).

FIGURE 95. Environment of and collecting sites at Lebu Valley (勒布沟). Forests at 2400 m (A, B), and 3650 m (C, D).