Trechus franzianus, Mateu & Deuve, 1979

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 : 24-25

The Trechus franzianus group

Diagnosis: Head with frontal furrows deep, +/- strongly curved at middle. Frons and supraorbital areas moderately convex. Temples smooth ( T. pumoensis Deuve, 1997 ) or indistinctly pubescent, with several very fine and very short hairs. Mandibles normal. Pronotum subcordate, with hind angles well produced. Pronotal base rectilinear or the outer fifth slightly 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 moderately impressed from level of the fifth umbilicate pore and deeply impressed from level of the seventh umbilicate pore backwards (only T. pumoensis ), or almost completely reduced, but sometimes visible at levels of seventh and eighth umbilicate pores (all other species). Recurrent elytral preapical sulcus deeply impressed and directed to the end of the fifth stria. Ventral surface smooth. Legs rather slender with moderately thick femora and relatively thin tibia and tarsi; protibiae distinctly dilated towards apices, hardly bowed, each without a longitudinal groove on external surface. Two basal protarsi of male dilated, dentoid at the inner apical border. Aedeagal median lobe elongated, with left and/or right sides widened behind middle, seen dorsally, with basal bulb moderately or strongly bent downwards, seen laterally, and with basal velum +/- largely developed. Lateral margin of median lobe with undulate curve before apex, and with terminal lamella not hooked. Internal sac with sclerotized portion relatively small and simple, saccate or reticulate. Parameres average to elongated, more slender towards tip, both with four setae; left paramere slightly longer than right one.

Remarks: Due to remarkable similarities in aedeagal characters (strongly elongated form of median lobe, apically shifted internal sac sclerotized portion) the species of the T. franzianus group resemble T. gitzeni Belousov & Kabak, 2001 from the Tian Shan mountain range of the Chinese province of Xinjiang. However, this character combination is surely the result of a convergent development because many external characters argue against closer relationships between these two these groups: T. gitzeni is much larger in body size, has a quite different form of frontal furrows of head, has iridescent elytra due to serrate and strongly transverse lines of microsculpture, and has the foretibiae strongly grooved on the anterior surface. In addition, the lateral margin of the aedeagal median lobe of T. gitzeni lacks the apical sinuation that is characteristic for all species of the T. franzianus group. Particularly this apical sinuation, but also the strongly elongated middle portion of the aedeagal median lobe as well as its widened distal portion, all these conspicuous characters make the T. franzianus group distinctive within the Trechus faunas of Tibet and the Himalaya .

Species included: T. aedeagalis sp. n. ( Nepal), T. eremita sp. n. ( Nepal), T. franzianus Mateu & Deuve, 1979 ( Nepal) , T. muguensis sp. n. ( Nepal), T. pumoensis Deuve, 1997 (South Central Tibet), T. sculptipennis sp. n. ( Nepal), T. tilitshoensis Schmidt, 1994 ( Nepal) .