Xiangxius Tian & X. Huang, 2021

Tian, Mingyi, Huang, Xinglong & Li, Chenliang, 2021, Contribution to the knowledge of subterranean ground beetles from eastern Wuling Mountains, China (Coleoptera: Carabidae: Trechinae), Zootaxa 4926 (4), pp. 521-534 : 522

Xiangxius Tian & X. Huang , n. gen.

Type species: Xiangxius jiangi Tian & Huang , n. sp. (the cave Tangle Dong, Jishou , Hunan) .

Generic characteristics. Medium-sized for cavernicolous trechine beetles, aphaenopsian and depigmented; body elongate, with thin and slender appendages. Head strongly elongate; genae slightly expanded at sides; two pairs of supra-orbital setiferous pores present; frontal furrows short and reduced, ending just behind the level of anterior supraorbital pores; vertex strongly convex; right mandibular tooth bidentate; labial suture completely disappeared; mentum densely pubescent at base of tooth apart from presence of two long setae, base largely and deeply concave; submentum with a row of 15–16 setae; antennae thin and long, but not extending over apices of elytra. Propleura visible from above; pronotum cylindrical, distinctly elongated, lateral margins nearly parallel-sided, presence of two pairs of latero-marginal setae (two additional setae present near the anterior seta on each side in the holotype specimen), both of fore and hind angles obtuse. Elytra elongated ovate, with a distinct humeral angle on each side; slightly longer than fore body including mandibles; lateral margins smooth, well-bordered throughout; disc strongly convex, striae noticeable though very weak, almost obsolete; two pairs of dorsal setiferous pores present on the 3 rd stria, preapical pores absent; the humeral group of the marginal umbilicate pores not aggregated, 1 st pore inwardly and backwardly shifted, 5 th and 6 th pores widely spaced. Only 1 st protarsomere modified in male, which is widened and distinctly denticulate inwardly at apex. Ventrite VII with one pair of apical setae in male, whereas two pairs in female. Male genitalia quite short but elongated, moderately sclerotized, blunt at apex.

Remarks. Xiangxius has the following peculiar characters: the protruding humeral angles on elytra; pubescent mentum; multisetose submentum; narrower pronotum which is as wide as head; and the peculiar elytral chaetotaxy: dorsal and marginal umbilicate pores are large and extraordinarily marked, 1 st pore of the marginal umbilicate series inwardly and backwardly shifted on 6 th striae and at a level behind 3 rd pore, and the 5 th and 6 th pores of the middle group widely spaced, making the distance from 6 th pore to 5 th as long as to 7 th. The character of protruding hemeral angles on elytra is unique among Chinese cave trechines. We hope phylogenetic analysis based on morphological and molecular data would be helpful to determine its position within subterranean trechines in near future.

Etymology. “ Xiangxi ”+ “- us ”. Xiangxi means western Hunan in Chinese. To refer to the homeland of this new genus. Gender masculine.

Generic range. China (Hunan) ( Fig. 1 ).

Figures

FIGURE 1. A distribution map showing the locality caves of the three new species described in the present paper (Tangle Dong: Xiangxius jiangi Tian & X. Huang, n. gen., n. sp. and Guizhaphaenopsodes solidior Tian & X. Huang, n. gen., n. sp.; Qizimei Dong: Sinotroglodytes hefengensis Tian & Li, n. sp.).