Trechus thibetanus, Jeannel R. Jeannel, 1928

Schmidt, Joachim, 2009, Taxonomic and biogeographical review of the genus Trechus Clairville, 1806, from the Tibetan Himalaya and the southern central Tibetan Plateau (Coleoptera: Carabidae: Trechini) 2178, Zootaxa 2178 (1), pp. 1-72 : 11-13

The Trechus thibetanus group

[ Trechus quadristriatus group sensu Jeannel (1927): partim; Trechus thibetanus group sensu Casale (1979): partim; Trechus cameroni group sensu Deuve (1996)]

Diagnosis: Head with frontal furrows deep and strongly curved at middle. Frons and supraorbital areas strongly convex. Temples convex, smooth. Mandibles rather stout. Pronotum transverse, with hind angles poorly developed. Pronotal base with outer quarters distinctly angulated anteriorly. Pronotal basal transverse depression and laterobasal foveae linear and sharply limited towards the convex disc. Pronotal median line distinct, not or slightly deeper near base. Hind wings reduced to small stubs. Humerus broadly rounded. Each elytron with parascutellar seta, preapical seta and two discal setae on third interval, with anterior discal seta located on stria III at the end of the anterior elytral quarter, and with middle dorsal seta located on stria III somewhat behind elytral middle. Stria VIII deeply impressed behind the level of the fifth umbilicate pore. Recurrent elytral preapical sulcus deeply impressed and directed to the end of the fifth stria. Ventral surface smooth. Legs moderately short with fairly thick femora and rather thin tibia and tarsi; protibiae moderately dilated towards apices and hardly bowed; longitudinal groove on external surface of protibia more strongly reduced, shallow and indistinct or absent. Two basal protarsi of male dilated, dentoid at the inner apical border. Aedeagal median lobe +/- evenly rounded in basal half, seen laterally, with basal bulb of average size but with basal velum relatively large. Median lobe apex not hooked. Internal sac with sclerotized portion separated into two distinct parts, both of which are elongated towards the ostium; the ostium is capped by the bent or lobed tip of the longer internal sac sclerotized part (copulatory piece). Parameres relatively slender, with left paramere distinctly longer than right one, both with four or five setae at tip.

Remarks: According to apomorphic pronotal character states the T. thibetanus group in the sense of this paper is part of the highly diverse Palaearctic T. quadristriatus species group sensu Jeannel (1927). Based on the current state of knowledge, the monophyly of the T. thibetanus group is difficult to prove because a comprehensive character analysis of the T. quadristriatus species group is still needed. This is, however, beyond the intent of the present paper. In part I am following Casale (1979) who understood the T. thibetanus group in a much wider sense but here I am excluding those species more closely related to T. indicus Putzeys, 1922 ( T. indicus group sensu Jeannel 1927) which have different aedeagal characters to those described in the diagnosis above and which have a perfectly developed longitudinal groove on external surface of protibiae. Due to striking similarities in the external shape of aedeagal median lobe and the general structure of sclerotized internal sac portions species of the T. thibetanus group in the sense of this paper seems to be more closely related to the following species of the fauna of the High Himalaya of Western Nepal: T. anae Morvan, 1981 , T. boudikae Morvan, 1981 , T. gradloni Morvan, 1981 , T. gwiomarchi Morvan, 1981 , T. jarrigei Morvan, 1972 , T. ledouxianus Mateu & Deuve, 1979 , T. levillaini Morvan, 1981 , T. perpusillus Mateu & Deuve, 1979 , T. roparzhemoni Morvan, 1981 , T. soma Mateu & Deuve, 1979 , T. yengensis Morvan, 1981 . However, all the latter species also possess a distinct longitudinal groove on the external surface of protibiae which is more strongly reduced in the species of the T. thibetanus group.

Species included: T. boulbeni Deuve, 1997 ( China, Gansu), T. cameroni bistriatus Jeannel, 1928 ( India, Punjab), T. cameroni cameroni Jeannel, 1923 ( India, Punjab), T. dongulaensis sp. n. (South Central Tibet), T. eutrechoides eutrechoides Deuve, 1992 (South Central Tibet), T. eutrechoides mondaensis Deuve, 1997 (South Central Tibet), T. glabratus sp. n. (South Central Tibet), T. namtsoensis sp. n. (South Central Tibet), T. thibetanus Jeannel, 1928 (South Central Tibet), T. thorongiensis Schmidt, 1994 (Tibetan Himalaya , Nepal).