Trechus budhaensis, 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 : 43-44

Trechus budhaensis sp. n.

( Fig. 62 )

Type material: Holotype male, with label data “ TIBET South Centr. 17–20.VI.07, Budha Vall. N of Yangpachem, ca. 30°10’56N 90°29’21E, 5000–5200 m ” ( CSCHM).

Paratypes: 1 male, 1 female, South Central Tibet, Budha Vall. N of Yangpachem, 5300–5600 m, ca. 30°11’07N 90°28’42E, 19.VI.2007 ( CSCHM) .

Description: Body length: 3.9–4.3 mm.

Colour: Dorsal surface brown, moderately shiny, with head somewhat darker than pronotum and elytra. Antennae, palpi and legs yellowish brown; distal portion of antennal segments II–IV as well as antennal segments V–XI on the whole darkened.

Microsculpture: Faintly engraved almost isodiametric meshes on supraorbital area and on pronotum, visible under high magnification only (x100), and more deeply engraved meshes on neck, in frontal furrows of head and in pronotal basal depression. Elytral disc with slightly engraved slightly transverse meshes in both sexes (x60–x80).

Head: More slender, with eyes small and slightly protruding. Temples approximately 3/4 of length of eyes and moderately wrinkled to the neck. Frontal furrows distinctly flattened at level of hind suborbital seta. Antennae more slender, 3.5 antennomeres extend beyond the pronotal base. Antennomere III distinctly longer than antennomere II and IV, both the latter are alike in length.

Pronotum: Small and cordate, slightly transverse, with sides strongly contracted towards base; proportions WP/LP = 1.26–1.28, WP/WPB = 1.36–1.40, WP/WH = 1.13–1.16, WE/WP = 1.82–1.97. Surface strongly convex. Sides concave in posterior third. Hind angles large and slightly obtuse. Marginal gutter narrow, slightly widened towards laterobasal depressions. Base rectilinear in middle and strongly curved anteriorly at outer fifth; basal depressions smooth.

Elytra: Oval, broadest a little behind mid-length; proportion WE/LE = 1.47–1.52. Surface strongly convex, not flattened on disc. Sides with shoulders evenly rounded. Striae finely punctate, first and second stria deeply impressed throughout, third striae only reduced at base, fourth stria shallower, fifth and sixth striae very slightly impressed, and seventh stria hardly visible. Stria VIII slightly impressed from level of the fifth umbilicate pore backwards and more deeply impressed at levels of seventh and eighth pores. Recurrent elytral preapical sulcus connected with the end of the fifth or seventh stria. Intervals I–IV strongly convex. Preapical seta is located at the end of second stria and at the beginning of the posterior elytral tenth.

Legs: Moderately slender.

Male genitalia: Aedeagal median lobe slender and moderately small (LE/LA = 2.85–3.06), strongly curved basally and elongated towards apex. Basal bulb average. Terminal lamella relatively long, in lateral view strongly curved upwards towards tip. Internal sac poorly sclerotized: In lateral view with a thin but distinct longitudinal sheet somewhat below the ostium. Parameres slender.

Etymology: The specific name is derived from the type locality, the Budha Valley (adjective).

Identification: In external characters this new species is similar to T. hodeberti Deuve, 1997 , and T. mieheorum sp. n. of the T. dacatraianus group, but it is simply to identify by the widely different shape of the aedeagal median lobe, especially by the negligible internal sac sclerotisation. It differs from other species of the T. antonini group, with exception of T. yeti sp. n., by the more evenly rounded elytra, by the more slender legs and by the longer and more strongly curved terminal lamella of aedeagal median lobe. For differentiation from T. yeti sp. n. see the text for that species, below.

Relationships: Due to the more strongly curved terminal lamella of aedeagal median lobe this new species together with T. claudiae Deuve, 1996 from East Tibet, and T. antonini Deuve, 1997 as well as T. yeti sp. n. from Nyainqentanglha Shan, seem to form a natural group within the T. antonini species group. Due to synapomorphies in both external and male genitalia morphology, such as the more slender head, the more evenly rounded elytra, and the peculiar form of the terminal lamella of the aedeagal median lobe, the newly described species T. budhaensis sp. n. and T. yeti sp. n. (see below) are doubtless sister species.

Distribution: Fig. 100 . Currently only known from the Budha Valley on south slope of central Nyainqentanglha Shan Massif north of Yangpachem.

Habitat: Higher alpine zone; vertical distribution approximately 5000–5400 m. The three individuals of the type series were found under big stones on humid, gently inclined slopes, together with the much more frequent species T. astrophilus sp. n. and T. yak sp. n.

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 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.