Trechus antonini, Schmidt, 2009

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 : 42-43

The Trechus antonini group

Diagnosis: Head with frontal furrows deep, +/- strongly curved at middle, often flattened at level of hind suborbital pore. Frons and supraorbital areas strongly convex. Temples almost smooth, with several very fine, very short hairs which are hardly visible. Mandibles normal. Pronotum cordate or subcordate, with hind angles well produced. Pronotal base rectilinear or slightly convex in middle and with outer fifth +/- strongly curved anteriorly. Pronotal basal transverse depression diffuse limited towards disc; laterobasal foveae broadly developed. Pronotal median line distinct, 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 slightly or moderately impressed from level of the fifth umbilicate pore backwards and more deeply impressed at levels of seventh and eighth pores. Recurrent elytral preapical sulcus deeply impressed and directed to the end of the fifth stria, but often connected to the prolonged seventh stria due to the more strongly shortened fifth and sixth striae in most species. Ventral surface smooth. Legs short or moderately slender, with thick femora and thin tibia and tarsi; protibiae slightly dilated towards apices, hardly bowed, without a longitudinal groove on external surface. Two basal protarsi of male dilated, dentoid at the inner apical border. Aedeagal median lobe small or moderately small, with basal bulb average and strongly bent downwards, and with basal velum well developed; in dorsal view more slender, in lateral view with terminal lamella moderately long or short, the latter usually slightly curved upwards but not hooked at tip. Internal sac with more strongly sclerotized portion limited to an elongated and often bipartite structure below median lobe ostium: 1) in lateral view with a needle-like or a thorn-like folding structure which is partly surrounded by 2) a less sclerotized sheet or saclike fold; the sclerotisation of the latter or both these folding structures are, however, strongly or completely reduced in some species. Parameres average or stout, with left paramere slightly longer than right one, both with four (seldom on one side three) setae at tip.

Remarks: Beside a single species from Qamdo, Eastern Tibet, this group includes the majority of Trechus species from the Transhimalaya and the southern slope of the Nyainqentanglha Shan. Based on the character set mentioned above, t he T. antonini group differs markedly from all species groups hitherto known from the High Himalaya or Tibetan Himalaya . However, the differential characters are not so strong compared to several species from the eastern parts of the Tibetan plateau because they are based mainly on +/- extensive reductions of aedeagal internal sac sclerotized portions. Although these internal sac structures as well the general shape of the aedeagal median lobe are very similar between species of the T. antonini group, parallel development of these features is not unlikely, and monophyly of that group, at present, is quite difficult to prove.

Species included: T. anjuensis Deuve, 1997 ( South Eastern Tibet), T. antonini Deuve, 1997 ( South Central Tibet) , T. astrophilus sp. n. ( South Central Tibet) , T. budhaensis sp. n. ( South Central Tibet) , T. claudiae Deuve, 1996 ( East Tibet) , T. folwarcznyi Deuve, 1997 ( South Central Tibet) , T. lama sp. n. ( South Central Tibet) , T. pseudocholaensis kaqiensis Deuve, 1997 ( East Tibet) , T. pseudocholaensis pseudocholaensis Deuve, 1997 ( East Tibet) , T. rarus sp. n. ( South Central Tibet) , T. religiosus sp. n. ( South Central Tibet) , T. singularis sp. n. ( South Central Tibet) , T. tsampa sp. n. ( South Central Tibet) , T. tseringi sp. n. ( South Central Tibet) , T. yak sp. n. ( South Central Tibet) , T. yak shogulaensis ssp. n. ( South Central Tibet) , T. yeti sp. n. ( South Central Tibet) .