Dianotrechus Tian

Tian, Mingyi, Huang, Sunbin, Wang, Xinhui & Tang, Mingruo, 2016, Contributions to the knowledge of subterranean trechine beetles in southern China's karsts: five new genera (Insecta, Coleoptera, Carabidae, Trechinae), ZooKeys 564, pp. 121-156 : 127-130

Taxon classification Animalia Coleoptera Carabidae

Dianotrechus Tian gen. n.

Type species.

Dianotrechus gueorguievi Tian, sp. n. (Cave Dashi Dong, Kunming, Yunnan).

Diagnosis.

Small-sized and anophthalmic trechine beetles, with robust head, complete frontal furrows, bidentate right mandible, 4-setose mentum, fused mentum and submentum, short appendages, quadrate pronotum, widely spaced middle pores of the marginal umbilicate setiferious series and 6-setose ventrite VII in female.

Generic characteristics.

Small-sized, anophthalmic trechine; unpigmented and apterous; head robust, genae strongly convex laterally; frontal furrows entire, two pairs of supra-orbital pores; right mandible bidentate; mentum and submentum completely fused; submentum 7-setose, a shorter seta present in the middle; mentum 4-setose; antennae short and stout, extending to basal third of elytra; prothorax with propleura invisible from above; pronotum quadrate, two pairs of laterodorsal setae present; elytra elongate-ovate, moderately convex, without prehumeral angles, lateral margins gently expanded, ciliated throughout; punctate-striate, two dorsal and the pre-apical pores present, apical stria present, humeral group of marginal umbilicate pores not aggregated, 5th and 6th pores of middle group widely separated, 5th pore strikingly shifted forward, much closer to 4th than to 6th; scutellum small; legs short and stout; protibia without longitudinal groove externally; ventrite VII in female with three pairs of setae.

Remarks.

The most striking peculiarities of this new genus lie in the conformation of the pronotum and the chaetotaxal pattern on the elytra, especially the middle group of umbilicate pores, in which the 5th pore is much closer to the 4th than to the 6th. Dianotrechus gen. n. seems to be particularly close to Shilinotrechus Uéno, 2003, an anophthalmic trechine genus also recorded from eastern Yunnan, but the former genus differs from the latter by the following character states: small-sized (versus medium-sized in Shilinotrechus ); right mandible bidentate (versus tridentate in Shilinotrechus ); body shape nearly parallel-sided (versus fusiform in Shilinotrechus ); head of anophthalmic type (versus aphaenopsian type in Shilinotrechus ); ventrite VII with three pairs of setae in female (versus two pairs in Shilinotrechus ). Some more differences are also evident in the conformation of the pronotum and elytra, as well as the chaetotaxy pattern of the marginal umbilicate series.

Compared to Cimmeritodes Deuve, 1996, a small-sized trechine genus originally reported from the Huoyan Karst of Longshan County, northwestern Hunan Province, but also occurring in Zhejiang ( Deuve and Tian 2015), Dianotrechus gen. n. is easily distinguished by the bidentate right mandible (versus tridentate in Cimmeritodes ), the quadrate pronotum (versus cordate in Cimmeritodes ), the chaetotaxy pattern of the marginal umbilicate series, in which the 5th is more distant from the 6th than from the 4 th (reverse in Cimmeritodes ), and ventrite VII has three pairs of setae in the female (two pairs in Cimmeritodes ).

Etymology.

Dian + Trechus, “Dian” is a short name for Yunnan Province in Chinese. The name of the new genus reflects the occurrence of this cavernicolous trechine in Yunnan. Gender masculine.

Range.

China (eastern Yunnan) (Fig. 5a).