Trechus astrophilus, 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 : 53-55

Trechus astrophilus sp. n.

( Figs. 65, 74 , 91 )

Type material: Holotype male, with label data “ TIBET ( South Central ) 19.VI.07, Budha Vall. N of Yangpachem, ca. 30°11’07N 90°28’42E, 5300–5600 m ” ( BMNH).

Paratypes: 52 males, 12 females, with same label data as holotype ( BMNH, CKAB, CSCHM, CWR, MNHN, SMNS) ; 1 male, 1 female, South Central Tibet, Budha Vall. N of Yangpachem, 5000–5200 m, ca. 30°10’56N 90°29’21E, 17–20.VI.07 ( CSCHM) .

Description: Body length: 3.2–3.9 mm.

Colour: Dorsal surface dark brown, shiny, with pronotum dark reddish brown. Scapus, basal segment of maxillary palpus and legs yellowish brown; distal half of antennal segment II, antennal segments IV–XI on the whole, second segment and basal portion of the third segment of maxillary palpus darkened.

Microsculpture: Supraorbital area and disc of pronotum almost polished, with very faintly engraved meshes, visible under high magnification only (x100). More deeply engraved almost isodiametric meshes in frontal furrows of head and in pronotal basal depression. Slightly engraved slightly transverse meshes on disc of elytra (x60).

Head: Average, with eyes small and slightly protruding; temples approximately 4/5 of length of eyes and strongly wrinkled to the neck. Frontal furrows slightly flattened at level of hind suborbital seta. Antennae average, 3 antennomeres extend beyond the pronotal base. Antennomere III slightly longer than antennomere II and IV, both the latter are alike in length.

Pronotum: Relatively small, cordate, moderately transverse and strongly contracted towards base; proportions WP/LP = 1.25–1.31, WP/WPB = 1.35–1.39, WP/WH = 1.15–1.20, WE/WP = 1.72–1.81. Surface strongly convex. Sides concave anterad of hind angles; the latter moderately large, sometimes slightly bent outwards, rectangular or slightly obtuse. Marginal gutter narrow, slightly widened anterad of laterobasal depressions. Base rectilinear or weakly convex in middle, more strongly curved anteriorly at outer fifth; basal depressions smooth.

Elytra: Oval, broadest almost at mid-length, with proportion WE/LE = 1.48–1.54. Surface strongly convex, not flattened on disc. Shoulders rounded, indistinct. Striae faintly or indistinctly punctate, first stria fully deep impressed, striae II–IV deeply impressed on disc but reduced at base and extreme apex, outer striae shallower, stria VII very faintly impressed but present. Stria VIII moderately 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 (-V) strongly convex. Preapical seta is located in the third interval distinctly before the end of the second stria and at the beginning of the last seventh of the elytra.

Legs: Relatively slender.

Male genitalia: Aedeagal median lobe average in length (LE/LA = 2.55–2.78), more strongly curved in basal half, slightly elongate towards apex, but with terminal lamella short; the latter slightly curved upwards. Basal bulb average. The structure of the sclerotized internal sac portion is distinctly bipartite, in dorsal view with a long needle-like copulatory piece which is surrounded by a more sac like sheet. Parameres slender.

Etymology: The specific name is derived from the Latinized Greek words “astrum” (starry sky) and “philum” (friend) and refers to the habitat of the new species which extends to exceptionally high altitudes, and which offer ideal condition to watch the stars; adjective.

Identification: In external characters similar to T. folwarcznyi Deuve, 1997 , but with body size on average larger, with head, antennae and legs somewhat slender, with temporae longer and with antennae darker. Moreover, T. astrophilus sp. n. is easily distinguished from all other species of the T. antonini group by the more extensively sclerotized aedeagal internal sac.

Relationships: T. astrophilus sp. n. and the below described T. lama sp. n. together share some conspicuous similarities in the shape of body and aedeagus which are considered to be synapomorphies and therefore, which indicate a sister species relationship: Antennae and legs more slender, elytra more evenly rounded, aedeagal median lobe more elongated towards apex. The above newly described species T. budhaensis sp. n. and T. yeti sp. n. share a similar body shape, however, based on apomorphic charater states of male genitalia both the latter species seem to belong to another evolutionary line which includes T. antonini Deuve, 1997 , a species with a shorter head and appendages and with less rounded elytra (see discussion above). Therefore, parallel evolution of similar external body shape characters are very likely in both the sister species pairs T. budhaensis - T. yeti and T. astrophilus - T. lama without indicating close relationships.

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

Habitat: Higher alpine zone. The species seems to be strictly limited to altitudes above 5200 m. Its vertical distribution extends to the upper limit of the alpine zone and adjoins the nival zone. Up to an altitude of 5600 m the species was frequently found under stones on gently inclined slopes in southern and western expositions as well on the top of an older moraine. At its highest occurrences, T. astrophilus sp. n. lives sympatrically with Amara altiphila Hieke, 1995 , and with a hitherto undescribed species of the Bembidion baehri group.

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 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.

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.