Sathytes sympatricus, 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 : 136-138

Sathytes sympatricus sp. nov.

( Figs 59 , 84C , 95A, B )

Chinese common name: ḲRḛà甲

Type material (16 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: 10 ♂♂, 5 ♀♀, same data as that of holotype (all paratypes in SNUC) .

Diagnosis. Male. Body length approximately 2.7 mm; ratio (length/width) of head 1.00–1.08, pronotum 1.05, elytra 0.83–0.84, length of eye/tempus 0.95. Antennomere 9 as long as wide (length/width excluding apophysis 1.0), with hyaline apophysis at middle of mesal margin, antennomere 11 elongate (length/width 1.64), with short protuberance at base, apex of protuberance with tuft of curved setae. Aedeagus broad, slightly constricted at middle, apical margin slightly emarginate and convex on right side. Female. Body length approximately 2.6 mm; antenna lacking modifications, genitalia as in Fig. 59G .

Description. Male. Body ( Fig. 59A ) length 2.66–2.68 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 59B ) sub-rectangular at base, approximately as long as wide, length 0.52–0.53 mm, width across eyes 0.53–0.56 mm, length/width 1.00–1.08; 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, shallowly impressed at middle; 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 17 large ommatidia, length of eye/tempus 0.95. Antenna elongate, length 1.33 mm, distinct club ( Fig. 59C ) formed by enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–7 each transverse, subequal in width, 8 as wide as and much shorter than 7, 9 ( Fig. 59D ) strongly enlarged, as long as wide, length/width excluding apophysis 1.0, mesal margin moderately expanded at middle and strongly oblique anteriorly and posteriorly, hyaline apophysis located at middle of mesal margin, 10 transverse, length/width 0.71, 11 largest, as long as 9 and 10 combined, length/width 1.64, with short, apically truncate protuberance at base, apex of protuberance with curved tuft of golden setae.

Pronotum ( Fig. 59B ) slightly longer than wide, length 0.58–0.61 mm, width 0.55–0.58 mm, length/width 1.05, widest at middle; lateral margins rounded, convergent apically and basally; disc weakly convex; large 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 0.82–0.86 mm, width 0.99–1.02 mm, length/width 0.83–0.84; each elytron with four large, asetose basal foveae; discal stria shallow and short; humerus weakly 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 fused, in oval opening, large lateral mesoventral foveae forked internally, mesoventral process short, with complete marginal stria. Metaventrite weakly prominent admesally, 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 0.77–0.78 mm, width 0.87–0.88 mm. Tergite 1 (IV) more than twice as long as 2 (V), lacking basal sulcus, with one pair of large 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. Sternites flat along middle; sternite 2 (IV) with one pair of mediobasal and three pairs of basolateral foveae, lacking lateral carina; 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. 59E ) moderately sclerotized, elongate, with few long setae along apical margin.

Aedeagus ( Fig. 59F ) 0.29 mm long, slightly asymmetric, plate-like; median lobe with large foramen, broad at base and slightly constricted at middle, apical margin moderately emarginate at middle and convex on right side.

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 2.56–2.59 mm; length/width of head 0.56/ 0.52–0.56 mm, pronotum 0.58–0.60/ 0.56–0.59 mm, elytra 0.76–0.77/ 0.97–0.99 mm; abdomen 0.77–0.80/ 0.93–0.94 mm; length of antenna 1.19–1.23 mm; maximum width of genitalia ( Fig. 59G ) 0.26 mm.

Comparative notes. The new species is related to a number of species centered on S. grandis , with all sharing a hyaline apophysis at the oblique mesal margin of antennomeres 9, and with a single basal protuberance consisting of a curved apical setose tuft on antennomere 11. Sathytes sympatricus differs particularly in the relatively small body size (2.7 mm), the long hyaline apophyses of antennomeres 9, the short basal protuberances of antennomeres 11, and the form of the aedeagus.

Distribution. Cona County, Tibet, SW China ( Figs 84C , 95A, B )

Etymology. The specific epithet ‘ sympatricus , - a, - um ’ is a Latin adjective indicating that this species is sympatric with a few congeners.

Figures

FIGURE 59. Morphology of Sathytes sympatricus 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 95. Environment of and collecting sites at Lebu Valley (勒布沟). Forests at 2400 m (A, B), and 3650 m (C, D).