Trechus solhoeyi, 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 : 41-42

Trechus solhoeyi sp. n.

( Figs. 59, 60 , 89 )

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 ” ( BMNH).

Paratypes: 27 males, 24 females, with same label data as holotype ( BMNH, CKAB, CSCHM, CWR, MNHN, SMNS) ; 18 males, 5 females, South Central Tibet, Budha Vall. N of Yangpachem, 4730–4900 m, ca. 30°10’38N 90°30’18E, 20.VI.2007 ( CSCHM) .

Description: Body length: 3.6–4.2 mm.

Colour: Dorsal surface shiny, with elytra dark brown, and with head, pronotum, elytral margin and first interval reddish brown. Antennae, palpi and legs yellowish brown. Distal third of antennal segment III and antennal segments IV–XI on the whole often darkened.

Microsculpture: Supraorbital area and disc of pronotum with faintly engraved meshes, visible under high magnification (x80–x100). Frontal furrows of head and pronotal basal depression with deeply engraved almost isodiametric meshes. Elytral disc with slightly engraved slightly transverse meshes in both sexes.

Head: Broad, with eyes moderately small and moderately protruding. Temples approximately 1/2 of length of eyes and strongly wrinkled to the neck. Frontal furrows deep between eyes and hardly flattened at hind suborbital seta. Antennae short, 2.5 antennomeres extend beyond the pronotal base. Antennomere III hardly longer than antennomere II, the latter is often slightly longer than antennomere IV.

Pronotum: Transverse, subcordate and strongly contracted towards base; proportions WP/LP = 1.31–1.39, WP/WPB = 1.29–1.34, WP/WH = 1.21–1.26, WE/WP = 1.54–1.57. Surface strongly convex, sides evenly rounded in anterior 2/3 and concave in posterior 1/3. Hind angles large, slightly obtuse (approximately 110°). Marginal gutter narrow, slightly widened towards laterobasal depressions. Base rectilinear in middle, slightly or moderately curved anteriorly at outer fifth; basal depressions sometimes with faint longitudinal wrinkles.

Elytra: Sub-oval, moderately stout, broadest a little behind mid-length; proportion: WE/LE = 1.49–1.53. Surface strongly convex, not flattened on disc. Sides slightly rounded in elytral middle and more strongly rounded towards apex, but almost straight at level of fourth umbilicate pore; shoulders rounded but distinct and relatively broad. Striae punctate, first stria deeply impressed throughout, second and third striae deeply impressed on disc and flattened or reduced at base and apex, outer striae distinctly finer, seventh stria hardly visible. Intervals I–IV slightly convex. Preapical seta is located at the end of second stria and at the beginning of the posterior elytral ninth or tenth.

Male genitalia: Aedeagal median lobe moderately large (LE/LA = 2.26–2.36), strongly curved basally and elongated towards apex. Terminal lamella moderately long, in lateral view slightly curved upwards, its base slightly stepped from level of ventral margin of median lobe. Internal sac extensively sclerotized: In dorsal view with two symmetrical folds extending at both sides of middle of median lobe towards apex; close to their base these folds enclose another but much smaller triangular or trapezoid sheet.

Etymology: I dedicate this species to my friend Torstein Solhøy, University of Bergen, for his endeavour on zoological research on the Tibetan Plateau and to uplift scientific education of students of the Tibetan University and especially for his kind support of my own studies on the Plateau. Formed as a noun (name) in the genitive case.

Identification: Within the Trechus fauna of the Tibetan Plateau this new species is easily to recognize by the shape of the aedeagal median lobe and by the unique internal sac features, especially by the presence of one pair of extensively sclerotized, side symmetrical sheets of internal sac folding. In addition with a small single sheet in the middle of median lobe the internal sac folding is therefore produced tripartite. Species of the T. dacatraianus group have indeed also side symmetrical internal sac folding lobes however, these sclerotized lobes are quadripartite produced. Moreover, in these species the external shape of the aedeagal median lobe is quite different. On central Nyainqentanglha Shan Massif, T. solhoeyi sp. n. is sympatrically distributed with three other edaphic Trechus species ( T. astrophilus sp. n., T. budhaensis sp. n., T. yak sp. n.), and as well as major differences in male genitalia characters, T. solhoeyi sp. n. can also be easily distinguished from these other species using external characters: The head is broader, with larger eyes and shorter temporae (approximately 1/2 of length of eyes, but with at least 2/3 of length of eyes in the other species), the pronotal hind angles are more strongly produced, and the elytra are distinctly broader on shoulders due to less constricted elytral sides towards base.

Relationships: The presence of one pair of symmetrical sheets the of aedeagal internal sac folding indicates for closer relationships with the T. dacatraianus species group. However, due to the tripartite structure of internal sac folding as well as due to the more apomorphic states of some external characters (smooth temples, strongly deepened pronotal median line before base, more strongly reduced eighth elytral stria) the new species seem to represent a separated evolutionary line.

Distribution: Fig. 99 . Currently only known from the Budha Valley, which is a relatively small brook valley on the south slope of central Nyainqentanglha Shan Massif north of Yangpachem.

Habitat: Lower alpine zone; vertical distribution approximately 4800–5100 m. The species was frequently found under stones on humid slopes and near to the Budha brook of the Budha 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.

FIGURES 87–92. Habitus. Fig. 87, Trechus martinae sp. n., paratype, female. Fig. 88, T. mieheorum sp. n., holotype. Fig. 89, T. solhoeyi sp. n., paratype, male. Fig. 90, T. yeti sp. n., holotype. Fig. 91, T. astrophilus sp. n., paratype, male. Fig. 92, T. tsampa sp. n., holotype.