Sathytes duojii, 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 : 123-124

Sathytes duojii sp. nov.

( Figs 53 , 83C , 97A, B )

Chinese common name: Ʒ吉ḛà甲

Type material ( 1 ex.). 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 ’.

Diagnosis. Male. Body length approximately 3.1 mm; ratio (length/width) of head 1.08, pronotum 1.03, elytra 0.82, length of eye/tempus 0.81. Antennomere 9 strongly enlarged, broad (length/width excluding apophysis 0.94), with hyaline apophysis slightly above middle of mesal margin, antennomere 11 elongate (length/width 1.53), with broad, moderately long protuberance at base, apex of protuberance with tuft of curved setae. Aedeagus broad at base and apex, constricted at middle.

Description. Male. Body ( Fig. 53A ) length 3.09 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 53B ) sub-rectangular at base, slightly longer than wide, length 0.63 mm, width across eyes 0.62 mm, length/width 1.02; 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, weakly impressed; clypeus with smooth surface, anterior margin carinate and moderately raised; ocular-mandibular carina distinct; postgenal region strongly projecting. Venter with small, broadly separated gular foveae (posterior tentorial pits), with faint median carina. Compound eyes prominent, composed of approximately 18 large ommatidia, length of eye/tempus 0.81. Antenna elongate, length 1.54 mm, distinct club ( Fig. 53C ) formed by enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–8 each transverse, 2 slightly wider, 3–8 subequal in width, 9 ( Fig. 53D ) strongly enlarged, slightly wider than long, length/width excluding apophysis 0.94, mesal margin oblique, hyaline apophysis located slightly above middle of mesal margin, 10 transverse, length/width 0.61, 11 largest, approximately as long as 9 and 10 combined, length/width 1.53, with broad protuberance at base, apex of protuberance with curved tuft of golden setae.

Pronotum ( Fig. 53B ) approximately as long as wide, length 0.71 mm, width 0.69 mm, length/width 1.03, 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 0.98 mm, width 1.19 mm, length/width 0.82; each elytron with four large, asetose basal foveae; discal stria represented by shallow and short impression near base; 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, inclined towards middle, with well-developed lateral mesocoxal and two lateral metaventral foveae, with small, 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 0.88 mm, width 1.06 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. 53E ) moderately sclerotized, elongate, apical margin with three long setae.

Aedeagus ( Fig. 53F ) 0.30 mm long, slightly asymmetric, plate-like; median lobe with large foramen, broad at apex and base, moderately constricted at middle, apical margin slightly emarginate at middle.

Female. Unknown.

Comparative notes. This species shares with S. caichenyangi the similar forms of male antennomeres 9, but can be readily separated by the smaller body size (3.1 mm vs. 3.5 mm), a less elongate head (ratio: 1.02 vs. 1.13), the shorter basal protuberances of antennomeres 11, and a more strongly constricted middle part of the generally stouter aedeagus.

Distribution. Bomê County, Tibet, SW China ( Figs 83C , 97A, B ).

Etymology. The new species is dedicated to Duoji Ciren, the driver and guide of our 2021 field trip in Tibet, who provided various kinds of help.

Figures

FIGURE 53. Morphology of Sathytes duojii sp. nov., male. A. Dorsal habitus. B. Head and pronotum. C. Antennomeres 9–11. D. Antennomere 9. E. Sternite 7 (IX). F. Aedeagus, ventral. Scale bars: 0.5 mm in A; 0.3 mm in B, C; 0.1 mm in D–F.

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 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).