Sichuanotrechus dakangensis Huang and Tian

Huang, Sunbin & Tian, Mingyi, 2015, New Species and New Record of Subterranean Trechine Beetles (Coleoptera: Carabidae: Trechinae) from Southwestern China, The Coleopterists Bulletin 69 (4), pp. 727-733 : 730-732

Sichuanotrechus dakangensis Huang and Tian , new species

( Figs. 7–9 , 13 )

Holotype. Male. CHINA: Zhaojia Dong cave, Xinghuo Cun San Zu, Dakang Zhen, Jiangyou Shi, Sichuan Province, 31°50′15.69″ N, 104°43′22.26″ E, 574 m, 17-VII-2014, Weixin Liu, Haomin Yin, Sunbin Huang and Xinhui Wang leg., deposited in SCAU; Paratypes: two females, with same data as holotype. front; eyeless; mandibles falcate, acute at apices, tridentate; mentum separated from submentum by faint labial suture, both furnished with several hairs; frons and vertex moderately convex, frontal furrows deep, arcuate from base of clypeus to occipital suture; genae slightly arcuate, with several setae; neck robust, constricted anteriorly; antenna slender, filiform, extending to apical 3/5 of elytra, scape thickest and as long as pedicel, antennomeres 3 to 5 longest, subequal in length, gradually shorter towards antennomere 10, antennomere 7 as long as 11. Pronotum: Slightly broader than in S. albidraconis , widest at level between 4/7 and 5/7 from base; PW /HW = 1.30–1.32 (mean 1.31), PW / PL = 0.98– 0.99 (mean 0.99); sides moderately arcuate, with 2 pairs of marginal setae; apex distinctly narrower than base, PbW/PfW = 1.11–1.13 (mean 1.12), front distinctly emarginate, front angles rounded; base nearly straight, hind angles pointed, moderately angulate; dorsum slightly convex, median line visible; apical transverse impression distinct and emarginate; basal transverse impression uneven along basal foveae. Scutellum small and narrowed. Elytra: Widest at level between basal 1/2 and 3/5; EW/ PW = 1.68–1.79 (mean 1.72), EL/ PL = 2.87–2.96 (mean 2.91), EL/EW = 1.61–1.78 (mean 1.70); shoulders distinct and rounded; sides glabrous, not serrulate, rounded at humeral parts and slightly arcuate until portion of middle dorsal pore, then gradually curved towards apices; dorsum moderately convex in middle, more declivous at outer and apical areas; striae entire, punctate and deeply impressed; apical carina obtuse; chaetotaxy identical to S. albidraconis . Ventral surface and legs: As in S. fusiformis , anal ventrite provided with a pair of marginal setae in male and 2 pairs in female, protarsomere 1 and 2 moderately dilated in male. Male genitalia: Median lobe similar to that of S. albidraconis ( Figs. 10, 11 ), about 3/10 as long as elytra, falciform, moderately sclerotized, feebly dilated from middle towards apex, but distinctly contracted on both sides at apical part ( Figs. 8, 9 ); basal orifice emarginate; in dorsal view, apical part of median lobe tumid and twisted, widest at the level of base of apical orifice, apical lobe slightly and evenly contracted towards apex; each paramere bearing 4 apical setae.

Remarks. Sichuanotrechus dakangensis is very similar to S. albidraconis , but differs from it by possessing a broader pronotum, aedeagus with a larger basal orifice, and much longer but narrower apical lobe.

Etymology. The species epithet “ dakangensis ” refers to the type locality.

Distribution. Known only from the type locality, Zhaojia Dong cave in Dakang, Jiangyou, northern Sichuan Province, China ( Fig. 12 ). Zhaojia Dong is an outflow cave, which provides a source of water for the local people. There are two entrances to the cave, the inaccessible efflux entrance, which is larger with plunge pools, and the upper, smaller entrance which is accessible. The passage is bumpy, moist, muddy, or full of holes on the substratum. Since the passage ahead is narrow, we do not know how long the cave is. The trechine beetles were found on the mud ( Fig. 13 ) in the dark area about 10 m from the entrances. Other cave animals living in the cave are crickets, millipedes, bats, and amphipods.

Uéno (2008) identified three female Sichuanotrechus specimens collected from Foye Dong as S. albidraconis . As Foye Dong is much closer to Zhaojia Dong (2.5 km) than to Bailong Gong cave (10 km), the type locality of S. albidraconis , we presume that the beetles must be members of S. dakangensis rather than of S. albidraconis .

Figures

Fig. 7. Sichuanotrechus dakangensis, habitus.

Figs. 8–9. Sichuanotrechus dakangensis, male genitalia. 8) Lateral view; 9) Dorsal view.

Fig. 13. Adult Sichuanotrechus dakangensis in Zhaojia Dong cave.

Figs. 10–11. Sichuanotrechus albidraconis, male genitalia. 10) Lateral view; 11) Dorsal view.

Fig. 12. Distribution map of genus Sichuanotrechus species. a = Yu Dong; b = Yuanwang Dong; c = Liangshui Dong; d = Bailong Gong Cave; e = Shuimen Dong; f = Xiniu Dong; g = Heiguaizi Dong; h = Zhaojia Dong; I = Foye Dong. D = S. wani; ♦ = S. albidraconis; ★ = S. rhinoceros Uéno, 2006; m = S. anxuanensis Uéno, 2008; j = S. dakangensis.