Trechus singularis, 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 : 51-52

Trechus singularis sp. n.

( Figs. 37 , 67 )

Type material: Holotype male, with label data “ TIBET ( South Central ) 5.VII.07, W of Shogu La 4650–4850 m 29°15’18N 90°04’06E to 29°48’15N 90°02’21E ” ( CSCHM).

Description: Body length: 3.5 mm.

Colour: Surface yellowish brown, moderately shiny, head somewhat darker brown. Appendages yellowish brown, but second segment of maxillary palpus and antennal segments III–XI indistinctly darkened.

Microsculpture: Surface of head with almost isodiametric meshes throughout, more deeply engraved in frontal furrows and on neck, but also distinct on supraorbital area (x50). Discs of pronotum and elytra with faintly engraved meshes (x80); mesh patterns more transverse on elytra.

Head: Stout and broad, with eyes small and slightly protruding; temples approximately 2/3 of length of eyes and strongly wrinkled to the neck. Frontal furrows somewhat flattened at level of hind suborbital seta. Antennae stout, 2 antennomeres extend beyond the pronotal base. Antennomere III distinctly longer than antennomere II and IV, both the latter are alike in length.

Pronotum: Sub-cordate, transverse and more strongly contracted towards base; proportions WP/LP = 1.28, WP/WPB = 1.30, WP/WH = 1.28, WE/WP = 1.53. Surface strongly convex. Sides convexly rounded in anterior 7/8 and curtly concave anterior hind angles, the latter relatively small and slightly obtuse (100). Marginal gutter narrow, slightly widened anterad of laterobasal depressions. Base slightly convex in middle and little more strongly curved anteriorly at outer fifth. Basal depressions with fine longitudinal wrinkles beside middle of pronotum.

Elytra: Sub-oval, with sides slightly contracted at the end of the anterior quarter and broadest a little behind mid-length; proportion WE/LE = 1.49. Surface strongly convex, slightly flattened on disc. Shoulders rounded but distinct. Striae finely punctate, first stria fully deep impressed, striae II–III deeply impressed on disc but flattened at base and extreme apex, outer striae shallower, stria VII hardly visible. Stria VIII slightly impressed from level of the fifth umbilicate pore backwards. Recurrent elytral preapical sulcus connected with the end of the seventh stria. Intervals I–IV strongly convex. Preapical seta is located in third interval and at the beginning of the posterior elytral seventh.

Legs: Stout.

Male genitalia: Aedeagal median lobe short (LE/LA = 3.09), in lateral view strongly curved, and with terminal lamella short and slightly bent upwards. Basal bulb average. Internal sac without distinct copulatory piece; the elongated folding structure below median lobe ostium is moderately sclerotized throughout. Parameres rather stout.

Etymology: The name is derived from the Latin word “singular-is, -e” and given due to the apparent rarity of the new species; only a single specimen has been found to date; adjective.

Identification: Larger than T. folwarcznyi Deuve, 1997 and T. tsampa sp. n., with pronotum more transverse and elytra broader on shoulders, and with aedeagal internal sac less sclerotized, without presence of a distinct copulatory piece. In male genitalia characters more similar to T. rarus sp. n., but easily to distinguish by slender head with smaller and less protruding eyes, and by the more strongly reduced micromeshes on supraorbital area.

Relationships: See chapter Relationships of T. tsampa sp. n.

Distribution: Fig. 100 . Mountainous areas south of Jomo Gangtse Peak at western Nyainqentanglha Shan Massif.

Habitat: The single specimen was found on yak meadows under a stone close to a brook.

Figures

FIGURE 100. Map of Southern Central Tibet showing distribution of species of the Trechus antonini group (white circles). 1, T. antonini Deuve, 1997. 2, T. religiosus sp. n. 3, T. astrophilus sp. n. 4, T. budhaensis sp. n. 5, T. rarus sp. n. 6, T. yeti sp. n. 7, T. folwarcznyi Deuve, 1997. 8, T. yak yak ssp. n. 9, T. yak shogulaensis ssp. n. 10, T. tseringi sp. n. 11, T. singularis sp. n. 12, T. tsampa sp. n. 13, T. lama sp. n.

FIGURES 36–38. Head, pronotum. Fig. 36, Trechus rarus sp. n., holotype. Fig. 37, T. singularis sp. n., holotype. Fig. 38, T. tseringi sp. n., paratype, male.

FIGURES 65–80. Aedeagal median lobe with sclerotized portions of internal sac in lateral view (Figs. 65–71, 77–80; Figs. 65, 68–71, 79, 80 in addition with parameres) and in dorsal view (Figs. 72–76). Figs. 65, 74, Trechus astrophilus sp. n., paratype. Fig. 66, T. lama sp. n., paratype. Fig. 67, T. singularis sp. n., holotype. Fig. 68, T. tsampa sp. n., paratype. Figs. 69, 76, T. yak yak ssp. n., paratype. Figs. 70, 73, T. religiosus sp. n., paratype. Figs. 71, 72, T. chaklaensis sp. n., paratype. Fig. 75, T. yak shogulaensis ssp. n., paratype. Fig. 77, T. antonini sp. n., non-type specimen from Lhachen La (= locus typicus). Fig. 78, T. folwarcznyi Deuve, 1997, non-type specimen from Shogu La (= locus typicus). Fig. 79, T. rarus sp. n., holotype. Fig. 80, T. tseringi sp. n., paratype.