Sathytes laticornis, 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 : 125-126

Sathytes laticornis sp. nov.

( Figs 54 , 83C , 95A, B )

Chinese common name: ÝƟḛà甲

Type material (6 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: 5 ♀♀, same data as that of holotype ( SNUC) .

Diagnosis. Male. Body length approximately 2.1 mm; ratio (length/width) of head 1.07, pronotum 1.02, elytra 0.77, length of eye/tempus 0.81. Antennomere 9 moderately transverse (length/width excluding apophysis 1.0), with hyaline apophysis at approximately middle of mesal margin, antennomere 11 elongate (length/width 1.71), with short protuberance at base, apex of protuberance with tuft of curved setae. Aedeagus broadly rounded at base, broadening through length, apical margin moderately emarginate. Female. Body length 2.1–2.2 mm; antenna lacking modifications, genitalia as in Fig. 54G .

Description. Male. Body ( Fig. 54A ) length 2.08 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short, dense pubescence.

Head ( Fig. 54B ) sub-rectangular at base, slightly longer than wide, length 0.48 mm, width across eyes 0.45 mm, length/width 1.07; vertex moderately raised, with small asetose foveae (dorsal tentorial pits); 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 median carina. Compound eyes moderately prominent, composed of approximately 18 large ommatidia, length of eye/tempus 0.81. Antenna elongate, length 1.04 mm, distinct club ( Fig. 54C ) formed by enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–8 each transverse, 2 slightly wider, 3–8 subequal in width, 9 ( Fig. 54D ) strongly enlarged, as long as wide, length/width excluding 1.0, mesal margin strongly expanded at middle, moderately inclined apically and basally, hyaline apophysis located at approximately middle of mesal margin, 10 transverse, length/width 0.75, 11 largest, as long as 9 and 10 combined, length/width 1.71, with short protuberance at base, apex of protuberance with curved tuft of golden setae.

Pronotum ( Fig. 54B ) approximately as long as wide, length 0.50 mm, width 0.49 mm, length/width 1.02, 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 0.67 mm, width 0.87 mm, length/width 0.77; each elytron with four small, asetose basal foveae; lacking discal stria; 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, 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 shallow, round median pit shortly anterior to posterior margin, posterior margin narrowly and shortly emarginate at middle.

Legs elongate, simple.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.57 mm, width 0.75 mm. Tergite 1 (IV) 2.5 times as long as 2 (V), lacking basal sulcus, with one pair of mediobasal and two pairs of basolateral foveae, lacking discal carinae, with indistinct, thin and short 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. 54E ) moderately sclerotized, elongate, apex with three long setae.

Aedeagus ( Fig. 54F ) 0.22 mm long, slightly asymmetric, plate-like; median lobe with large foramen, broadest at apical 1/3, apical margin emarginate at middle and moderately expanded at right side.

Female. Similar to male in external morphology; antenna slightly shorter, lacking modifications; each compound eye composed of approximately 12 ommatidia; humerus weakly prominent. Measurements (as for male): body length 2.11–2.20 mm; length/width of head 0.48–0.49/ 0.45–0.46 mm, pronotum 0.49–0.51/ 0.46–0.49 mm, elytra 0.60–0.64/ 0.84–0.85 mm; abdomen 0.64–0.67/ 0.81–0.82 mm; length of antenna 1.01–1.02 mm; maximum width of genitalia ( Fig. 54G ) 0.22 mm.

Comparative notes. The male of Sathytes laticornis differs from those of all congeners by the relatively broad antennomeres 9 (mesal margin less oblique), combined with the small body size (2.08 mm), the short basal protuberances of antennomeres 11, and the unique form of the aedeagus.

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

Etymology. The specific epithet is combined from the Latin adjective ‘ lâtus, - a, - um (wide, broad)’ and ‘ cornis (horned)’, referring to the broad shape of male antennomeres 9 of this species.

Figures

FIGURE 54. Morphology of Sathytes laticornis 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 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).