Trechus glabratus, 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 : 20-21

Trechus glabratus sp. n.

( Figs. 6 , 23 , 82 )

Type material: Holotype male, with label data “ TIBET South Centr. 6.VII.07, Doru Tshu Vall. SW Dongu La, 4500–4600 m, ca. 29°43’16N 89°47’12E ” ( SMNS) . Paratypes: 48 males, 41 females, with same label data as holotype ( BMNH, CGITZ, CKAB, CSCHM, CWR, MNHN, NMBE, SMNS) . 4 males, 2 females, W of Shogu La , 4650–4850 m, 29°15’18N 90°04’06E to 29°48’15N 90°02’21E, 5.VII.07 ( CSCHM) .

Description: Body length: 3.3–3.7 mm.

Colour: Dorsal surface shiny dark brown, antennae, palpi, legs, elytral and pronotal lateral margins, scutellar region and elytral suture light brown. Antennae often darkened from joint III or IV toward apex.

Microsculpture: Disc of head smooth, with very faintly engraved meshes (x120). Discs of pronotum and elytra polished; pronotal sides and elytral apex with micromeshes visible under high magnification (x150).

Head: Average sized, with eyes moderately small and slightly protruding. Temples approximately 2/5 times length of eyes, strongly wrinkled to the neck. Anterior part of frontal furrows deep, posterior part flattened towards hind suborbital seta. Antennae moderately short, three antennomeres extend beyond the pronotal base. Antennomere III distinctly longer than antennomeres II and IV, both the latter are alike in length.

Pronotum: Transverse; with sides moderately contracted towards base; proportions: WP/LP = 1.40–1.47, WP/WPB = 1.24–1.27, WP/WH = 1.28–1.32, WE/WP = 1.53–1.57. Surface strongly convex, sides evenly rounded and straight just anterad of posterior setae. Hind angles very poorly developed, obtuse or almost rounded. Marginal gutter narrow throughout. Basal groove smooth.

Elytra: Oval, broadest almost at mid-length; proportion: WE/LE = 1.46–1.52. Surface convex, not flattened on disc. Shoulders distinct but rounded. Striae faintly punctate, only first stria moderately deeply impressed overall, second stria moderately impressed but absent at base, outer striae only suggested as rows of very faintly engraved punctures in elytral middle or completely absent. Intervals I–II slightly convex. Preapical seta is located on the prolonged and strongly outwardly bent second stria near to apex at the beginning of the posterior elytral twelfth to fifteens part.

Male genitalia: Aedeagal median lobe moderately long (LE/LA = 2.72–2.79), evenly curved in basal 2/3 and straight toward apex, seen laterally. Terminal lamella relatively short, with apex stubby. Basal bulb average in size with velum large. Both the copulatory pieces thin and elongated, needle-like. Parameres moderately slender, each with four setae at tip.

Etymology: The species is named for the reduced elytral microsculpture on the body surface, an important diagnostic feature within the T. thibetanus species group (Latin “glabrat-us, -a, -um”: smooth); adjective.

Identification: Within the T. thibetanus group this new species is easily to recognize by the reduced elytral microsculpture on the one hand, and by the reduction of both the sclerotized parts of aedeagal internal sac to needle-like sclerites on the other hand.

Relationships: Up to now I could not find any synapomorphy with any other taxon of the T. thibetanus species group. Moreover, according to the derived copulatory pieces of aedeagal internal sac this new species seems to be quite isolated within the species group.

Distribution and geographical variation: Fig. 98 . Westernmost parts of Nyainqentanglha Shan Massif.

Habitat: Lower alpine zone; vertical distribution approximately 4500–4900 m. The species was frequently found under stones on yak pastures.

Figures

FIGURE 98. Map of central parts of Tibet and the Himalaya showing distribution of species of the Trechus thibetanus group (white circles), of the Trechus pumoensis group (white squares), of the Trechus rolwalingense group (black circles), and of the Trechus stratiotes group (black squares). 1, T. namtsoensis sp. n. 2, T. dongulaensis sp. n. 3, T. thibetanus Jeannel, 1928. 4, T. glabratus sp. n. 5, T. thorongiensis Schmidt, 1994. 6, T. eutrechoides eutrechoides Deuve, 1992. 7, T. eutrechoides mondaensis Deuve, 1997. 8, T. pumoensis Deuve, 1997. 9, T. tilitshoensis Schmidt, 1994. 10, T. franzianus Mateu & Deuve, 1979. 11, T. muguensis sp. n. 12, T. eremita sp. n. 13, T. aedeagalis sp. n. 14, T. sculptipennis sp. n. 15, T. rolwalingense rolwalingense ssp. n. 16, T. rolwalingense daldunglana ssp. n. 17, T. stratiotes stratiotes ssp. n. 18, T. stratiotes malikasthana ssp. n.

FIGURES 2–11. Pronotum. Fig. 2, Trechus thibetanus Jeannel, 1928, Lectotype. Fig. 3, T. dongulaensis sp. n., paratype, male. Fig. 4, T. namtsoensis sp. n., paratype, male. Fig. 5, T. eutrechoides eutrechoides Deuve, 1992, non-type male specimen from Lamna La. Fig. 6, T. glabratus sp. n., paratype, male. Fig. 7, T. korae sp. n., paratype, male. Fig. 8, T. yak yak ssp. n., paratype, male. Fig. 9, T. yak shogulaensis ssp. n., paratype, male. Fig. 10, T. rolwalingensis rolwalingensis ssp. n., paratype, male. Fig. 11, T. rolwalingensis daldunglana ssp. n., paratype, male.

FIGURES 12–27. Aedeagal median lobe with sclerotized portions of internal sac in lateral view (Figs. 12–18, 23–26; Figs. 14, 17, 23, 26 in addition with parameres) and in dorsal view (Fig. 27); apical portion of the longer copulatory piece (Figs. 19–22). Fig. 12, Trechus thorongiensis Schmidt, 1994, paratype, the arrow pointed to the prolongated basal portion of the shorter copulatory piece. Fig. 13, T. eutrechoides eutrechoides Deuve, 1992, non-type specimen from Rongshar Valley. Fig. 14, T. eutrechoides mondaensis Deuve, 1997, paratype. Figs. 15, 19, T. thibetanus Jeannel, 1928, holotype. Figs. 16, 20, T. thibetanus Jeannel, 1928, non-type specimen from Kampa La. Figs. 17, 21, T. dongulaensis sp. n., paratype. Figs. 18, 22, T. namtsoensis sp. n., paratype. Fig. 23, T. glabratus sp. n., paratype. Fig. 24, T. wrzecionkoi Deuve, 1996, non-type specimen from Gyama, Chungenpo Chong side valley. Fig. 25, T. korae sp. n., paratype. Figs. 26, 27, T. martinae sp. n., paratype.

FIGURES 81–86. Habitus. Fig. 81, Trechus dongulaensis sp. n., paratype, female. Fig. 82, T. glabratus sp. n., paratype, female. Fig. 83, T. rolwalingensis rolwalingensis ssp. n., holotype. Fig. 84, T. stratiotes stratiotes ssp. n., paratype, male. Fig. 85, T. muguensis sp. n., paratype, female. Fig. 86, T. sculptipennis sp. n., paratype, female.