Trechus rarus, 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 : 50-51

Trechus rarus sp. n.

( Figs. 36 , 79 )

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 ” ( CSCHM).

Paratypes: 1 female, with same label data as holotype ( CSCHM) .

Description: Body length: 3.3–3.4 mm.

Colour: Surface reddish brown, moderately shiny, head and posterior 2/3 of elytra cloudy dark brown. Palpi, scapus, pedicellus, basal half of antennal segment III and legs yellowish brown; distal half of antennal segment III as well as antennal segments IV–XI on the whole 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). Disc of pronotum almost smooth, with very faintly engraved meshes (x100). Faintly engraved slightly transverse meshes on disc of elytra (x80).

Head: Stout and broad, with eyes moderately small and moderately protruding; temples almost 1/2 of length of eyes and strongly wrinkled to the neck. Frontal furrows moderately deep in front and strongly flattened at level of hind suborbital seta. Antennae stout, 1.5–2 antennomeres extend beyond the pronotal base. Antennomere III somewhat longer than antennomere II and IV, both the latter are alike in length.

Pronotum: Sub-cordate, transverse and moderately contracted towards base; proportions WP/LP = 1.31–1.33, WP/WPB = 1.25–1.31, WP/WH = 1.14–1.18, WE/WP = 1.47–1.56. Surface strongly convex. Sides evenly rounded in anterior 2/3 and straight towards base; hind angles slightly obtuse (100–105°). Marginal gutter narrow, almost not widened anterad of laterobasal depressions. Base slightly convex in middle and little more strongly curved anteriorly at outer fifth. Basal depressions smooth.

Elytra: Oval, broadest a little behind mid-length, with proportion WE/LE = 1.49. Surface strongly convex, not flattened on disc. Shoulders rounded but distinct. Striae finely punctate, striae I–III deeply impressed but reduced at base, stria IV much shallower, stria V suggested as a row of finely engraved punctures, striae VI and VII hardly visible in anterior half but slightly impressed (incomplete, with interruptions) towards apex. Stria VIII moderately impressed from level of the fifth umbilicate pore backwards but with a +/- broad interruption of the stria in middle of distance between fifth and seventh pores. Recurrent elytral preapical sulcus connected with the interrupted and prolonged end of the fifth stria. Intervals I–IV moderately to strongly convex. Preapical seta is located close to the second stria and at the beginning of the posterior elytral eighth or ninth.

Legs: Stout.

Male genitalia: Aedeagal median lobe short (LE/LA = 3.23), in lateral view strongly but not evenly curved, with ventral side almost straight in middle of median lobe; terminal lamella short and slightly bent upwards. Basal bulb average. Internal sac with the more strongly sclerotized portions indistinctly separated in two elongated, thin and closed longitudinal sheets below median lobe ostium. Parameres rather stout.

Etymology: The name is given due to the apparent rarity of the new species (Latin “rar-us, -a, -um”); adjective.

Identification: In male genitalia characters, this new species is very similar to T. folwarcznyi Deuve, 1997 , and the newly described species T. singularis sp. n., and T. tsampa sp. n., however, it is easily to distinguish by the broader head with larger and more protruded eyes, and by the more deeply engraved micromeshes on disc of head. In addition, it differs in the external form of the aedeagal median lobe, which is, in lateral view, not so evenly curved as in the species mentioned above.

Relationships: See text on ‘Relationships’ under T. tsampa sp. n.

Distribution: Fig. 100 . Uppermost Shogu Tshu Valley of western Nyainqentanglha Shan Massif, east of Jomo Gangtse Peak.

Habitat: Humid meadows of the higher alpine zone; vertical distribution approximately 5000–5200 m.

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.