Sathytes dawai, 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 : 121-123

Sathytes dawai sp. nov.

( Figs 52 , 83B , 90 , 93F, G )

Chinese common name: ḭǟḛà甲

Type material (17 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: 11 ♂♂, 4 ♀♀, same data as that of holotype; 1 ♂ , ‘ China: Xizang, Gyirong County, Gyirong Valley, slope nr. Jifu Vill. , 28°22’37”N, 85°19’41”E, 2400-2700 m, 22.vi.2021, Z. Peng, Z. Yin & W. Zhang leg., ƱẪU喀NJ吉PW吉ė村ṉữ山坡 ’ (all paratypes in SNUC) .

Diagnosis. Male. Body length greater than 2.4 mm; ratio (length/width) of head 1.10–1.15, pronotum 0.96– 1.02, elytra 0.81–0.83, length of eye/tempus 0.95–1.13. Antennomere 9 slightly elongate (length/width excluding apophysis 1.18–1.23), with hyaline apophysis at middle of mesal margin, antennomere 11 elongate (length/ width 1.74–1.77), with single protuberance at base, apex of protuberance with tuft of curved setae. Aedeagus broad throughout length, with apex as broad as base. Female. Body length over 2.3 mm; antenna lacking modifications, genitalia as in Fig. 52G .

Description. Male. Body ( Fig. 52A ) length 2.42–2.51 mm; color reddish-brown, tarsi and mouthparts lighter. Dorsal surface of body covered with short pubescence.

Head ( Fig. 52B ) sub-rectangular at base, slightly longer than wide, length 0.52–0.53 mm, width across eyes 0.46–0.48 mm, length/width 1.10–1.13; vertex moderately raised, with distinct 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 present; postgenal region strongly projecting. Venter with small, broadly separated gular foveae (posterior tentorial pits), lacking median carina or sulcus. Compound eyes prominent, composed of approximately 20–22 large ommatidia, length of eye/tempus 0.95–1.13. Antenna elongate, length 1.25–1.32 mm, distinct club ( Fig. 52C ) formed by enlarged apical three antennomeres; antennomere 1 thick, subcylindrical, 2–8 each transverse, 2 slightly wider, 3–8 subequal in width, 9 ( Fig. 52D ) strongly enlarged, slightly elongate, length/width excluding apophysis 1.18–1.23, mesal margin moderately expanded at middle, hyaline apophysis located anterior to middle of mesal margin, 10 transverse, length/width 0.75–0.76, 11 largest, as long as 9 and 10 combined, length/width 1.74–1.77, with truncate protuberance at base, apex of protuberance with curved tuft of golden setae.

Pronotum ( Fig. 52B ) approximately as long as wide, length 0.53–0.56 mm, width 0.55 mm, length/width 0.96– 1.02, 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 0.73 mm, width 0.88–0.90 mm, length/width 0.81–0.83; each elytron with four large, asetose basal foveae; lacking discal stria; humerus roundly and 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 contiguous, originating from shared opening, large lateral mesoventral foveae forked internally, anteromesal margin of coxal cavity with small tubercle, mesoventral process short, with complete marginal stria. Metaventrite moderately 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 with indistinct, short split at middle.

Legs elongate, simple.

Abdomen widest at lateral margins of tergite 1 (IV), length 0.69–0.78 mm, width 0.77–0.78 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, discal and marginal carina thin and short, indistinct; 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. 52E ) moderately sclerotized, elongate, apex asetose.

Aedeagus ( Fig. 52F ) 0.31–0.33 mm long, slightly asymmetric, plate-like; median lobe with large foramen, broadened throughout entire length, with apex as broad as base.

Female. Similar to male in external morphology; antenna slightly shorter, lacking modifications; each compound eye composed of approximately 13 ommatidia; humerus weakly prominent. Measurements (as for male): body length 2.32–2.46 mm; length/width of head 0.50–0.52/ 0.45–0.47 mm, pronotum 0.51–0.55/ 0.53–0.55 mm, elytra 0.65/ 0.84 mm; abdomen 0.75–0.79/ 0.79–0.81 mm; length of antenna 1.08–1.12 mm; maximum width of genitalia ( Fig. 52G ) 0.27 mm.

Comparative notes. Sathytes dawai is morphological similar to S. montanus Löbl and S. grandis Löbl that are distributed in northern India and a number of Chinese species including S. alpicola Yin & Shen , S. panzhaohuii Yin & Shen , and S. xizangensis Yin & Shen from Tibet that share a hyaline apophysis on the more or less expanded mesal margin of antennomere 9, and a single basal projection of antennomeres 11. The new species, however, can be separated from all these congeners by a combination of characters listed in the ‘Diagnosis’ section, and especially by the elongate antennomere 9 with its more apical placement of the hyaline apophysis on it.

Distribution. Dinggyê and Gyirong County, Tibet, SW China ( Figs 83B , 90 , 93F, G ).

Etymology. The new species is named after Wa Da (ḭǟ), who provided logistical and other kinds of support during our field investigations in Tibet.

Figures

FIGURE 52. Morphology of Sathytes dawai 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 90. Environment of and collecting sites at Gyirong Valley. A. General environment of the valley. B. A slope dominated by conifers along the valley. C. Zhong Peng searching pselaphines under the bark of a fallen trunk.

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.