Trechus bastropi, 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 : 38-39

Trechus bastropi sp. n.

( Figs. 1, 55, 58 )

Type material: Holotype male, with label data “ TIBET South Centr. 3–4.VII.07, NE of Shogu La pass, 5000–5350 m, 29°54’48– 29°57’20N 90°08’28– 90°07’49E ” ( BMNH) . Paratypes: 18 males, 5 females, with same label data as holotype ( BMNH, CSCHM) .

Description: Body length: 4–4.5 mm.

Colour: Dorsal surface dark brown, moderately shiny, pronotum, elytral margin and first interval reddish brown. Antennae, palpi and legs yellowish brown.

Microsculpture: Discs of head and pronotum almost smooth, with very faintly engraved meshes, visible under high magnification only (x100). In contrast, pronotal basal depression with granulate sculpture due to strongly convex surfaces of sculpticells. Surface of elytra with moderately engraved slightly transverse meshes in both sexes.

Head: Average sized, with eyes relatively small and only slightly protruding. Temples approximately 3/4 of length of eyes and strongly wrinkled to the neck. Frontal furrows deep, somewhat flattened at level of hind suborbital seta. Antennae moderately short, three antennomeres extend beyond the pronotal base. Antennomere III slightly longer than antennomeres II and IV, both the latter are alike in length.

Pronotum: Slightly transverse and hardly cordate, with sides strongly contracted towards base; proportions WP/LP = 1.21–1.30, WP/WPB = 1.30–1.39, WP/WH = 1.16–1.27, WE/WP = 1.61–1.66. Surface strongly convex, sides evenly rounded in anterior 4/5–5/6 and straight or slightly concave just anterad of posterior setae. Hind angles relatively poorly developed, slightly obtuse (110–120°). Marginal gutter narrow, somewhat widened just anterad of laterobasal depressions. Base rectilinear or slightly convex in middle, but distinctly curved anteriorly at outer fifth. Basal depressions rough due to strongly convex discs of sculpticells of micromeshes, sometimes in addition of faint wrinkles at both sides of middle of base.

Elytra: Oval, broadest a little behind mid-length; proportion WE/LE = 1.39–1.48. Surface strongly convex, not flattened on disc. Sides rounded with shoulders indistinct. Striae impunctate or very finely and scarcely punctate, inner three striae deeply impressed on disc, but flattened or reduced at apex and base; outer striae shallower, but always distinct. Three or four inner intervals slightly convex. Preapical seta located on second stria and at the beginning of the posterior elytral sixth.

Male genitalia: Aedeagal median lobe large (LE/LA = 2.10–2.16), strongly curved basally and elongated towards apex. Basal bulb spherically enlarged but with velum narrow. Apex in lateral view with a long upwardly and finally inwardly curved hook. Internal sac extensively sclerotized: In dorsal view with two side symmetrical folds in middle of median lobe, whereas the inner fold forms a tent like structure, and the outer fold encloses the inner fold at its basal portion. In lateral view, an additional and less strongly sclerotized fold proceeds loop-like from the folding structures of median lobe middle towards apex below median lobe ostium.

Etymology: I dedicate this species to my dear colleague Ralf Bastrop, University of Rostock, who kindly taught me how to deal with molecular analysis of carabid beetles. Formed as a noun (name) in the genitive case.

Identification: Within the fauna of western Nyainqentanglha Shan Massif this species is easily to recognize by the large aedeagal median lobe, which is elongated in middle part and remarkably hooked at apex, but not double-hooked as in T. damchungensis Deuve, 1997 . It is similar to T. hodeberti Deuve, 1997 , from central Nyainqentanglha Shan, both in external and genital morphological characters, but has body darker and stouter, eyes slightly larger, frontal furrows of head not shortened behind, antennae and legs slightly shorter, elytral stria deeper, aedeagal median lobe more elongate, with apical hook much larger and internal sac more extensively sclerotized. For differentiation from T. mieheorum sp. n. see key to species and the diagnosis of the latter, below.

Relationships: According to the loop-like internal sac fold below median lobe ostium, which seems a synapomorphic character state of the species T. bastropi sp. n. and T. hodeberti Deuve, 1997 , a sister species relationship of both these species is very probably.

Distribution: Fig. 99 . Endemic species of western Nyainqentanglha Shan Massif. Currently only known from the NE slope of Shogu La pass, 40 km southwest of Yangpachem.

Habitat: High alpine zone; vertical distribution approximately 5000–5300 m. The species was found under big stones on humid slopes close to the bottom of the upper Shogu Tshu river valley.

Figures

FIGURE 99. Map of Southern Central Tibet showing distribution of species of the Trechus wrzecionkoi group (white circles), of the Trechus dacatraianus group (white squares), of the Trechus solhoeyi group (black circle), and of the Trechus chaklaensis group (black square). 1, T. wrzecionkoi Deuve, 1996. 2, T. martinae sp. n. 3, T. korae sp. n. 4, T. damchungensis Deuve, 1997. 5, T. hodeberti Deuve, 1997. 6, T. bastropi sp. n. 7, T. mieheorum sp. n. 8, T. solhoeyi sp. n. 9, T. chaklaensis sp. n.

FIGURES 52–64. Aedeagal median lobe with sclerotized portions of internal sac in lateral view (Figs. 52–56, 60–63; Figs. 52, 54, 55, 60, 61, 63 in addition with parameres) and in dorsal view (Figs. 57–59, 64). Fig. 52, Trechus damchungensis Deuve, 1997, holotype. Figs. 53, 57, T. cf. damchungensis Deuve, 1997, paratype from Tangula Pass. Fig. 54, T. mieheorum sp. n., paratype. Figs. 55, 58, T. bastropi sp. n., paratype. Fig. 56, T. hodeberti Deuve, 1997, nontype specimen from Lhachen La (= locus typicus). Figs. 59, 60, T. solhoeyi sp. n., paratype. Fig. 61, T. yeti sp. n., paratype. Fig. 62, T. budhaensis sp. n., paratype. Fig. 63, 64, T. rolwalingensis sp. n., paratype.