Trechus muguensis, 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 : 27-28

Trechus muguensis sp. n.

( Figs. 43, 44 , 85 )

Type material: Holotype male, with label data “ NEPAL oc. 30 km NE Jumla, Hochebene NE Dolphu Kang, 4100 m, 03.VII.1999, 29°28’N 82°25E leg. A. Weigel ” ( NME) . Paratypes: 6 males, 2 females, with same label data as holotype ( CSCHM, CWG, NME) ; 1 female, Nepal, Karnali Province, Mugu District , Sisne Himal, N Dolphu Kang, 3800–4100 m, 29°28’3N 82°24’4E, 2 VII.1999, leg. M. Hartmann ( NME) ; 3 males, 4 females, Nepal, Mugu District , N Pass Dolphu Kang, 4100–4300 m, 29°28N 82°24E, 3.VII.1999, leg. E. Grill ( CGR, CSCHM) .

Description: Body length: 3.2–3.7 mm.

Colour: Dorsal surface brown or light reddish brown, moderately shiny (males) or somewhat dull on elytra (females), head in some specimens somewhat darker than pronotum, palpi, three basal antennal segments and legs yellowish brown.

Microsculpture: Head almost smooth on disc, but with slightly engraved almost isodiametric meshes in frontal furrows and on neck. Pronotum with faintly engraved slightly transverse meshes on disc and deeply engraved meshes throughout basal depressions. Elytra with almost isodiametric meshes which are moderately engraved in males and more deeply engraved in females.

Head: Average sized, with eyes flat and small; temples as long as eyes, strongly wrinkled to the neck. Frontal furrows deep between eyes, flattened at level of 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: Cordate and transverse, with sides strongly contracted towards base; proportions: WP/LP = 1.25–1.31, WP/WPB = 1.38–1.46, WP/WH = 1.23–1.29, WE/WP = 1.53–1.65. Surface convex, sides evenly rounded in anterior 2/3, but concave bent towards hind angles; the latter well produced, slightly obtuse to almost rectangular. Base almost rectilinear, sometimes slightly curved anteriorly at outer fifth. Marginal gutter narrow, widened at laterobasal depressions, the latter somewhat rough due to strongly convex discs of sculpticells of micromeshes, often in addition with one or two punctiform impressions.

Elytra: Oviform, broadest a little behind mid-length; proportion: WE/LE = 1.46–1.50. Surface moderately convex, somewhat flattened on disc. Sides evenly rounded with shoulders indistinct. Striae usually impunctate, but sometimes with the suggestion of fine dots. First stria moderately deep on elytral disc, absent at base and flattened on apex; second and third striae slightly impressed only on disc; fourth and fifth striae only suggested as fine incomplete lines, sixth and seventh striae usually completely reduced. Second interval slightly convex. Preapical seta is located at the end of second stria and at the beginning of the posterior elytral sixth or seventh.

Male genitalia: Aedeagal median lobe elongate (LE/LA = 1.86–1.87), in lateral view strongly curved behind basal bulb, with ventral side slightly convex in middle with undulate curve before apex. In dorsal view, right side of median lobe somewhat widened at the beginning of distal quarter; tip of terminal lamella produced, truncate. Internal sac with sclerotized portion small, strongly flattened in lateral view.

Etymology: The specific epithet is derived from the type locality, the Mugu District of Western Nepal (adjective).

Identification: Body more complanate than T. pumoensis Deuve, 1997 , eyes distinctly smaller, antennae shorter, outer elytral striae more strongly reduced, aedeagal median lobe more elongated. Pronotal hind angles more strongly developed than T. tilitshoensis Schmidt, 1994 , the pronotal base not or slightly curved anteriorly towards basal setae, the micromeshes on vertex and frontal furrows more deeply engraved. In external characters almost identical to T. franzianus Mateu & Deuve, 1979 , but elytral microsculpture in females not such as deep engraved than in “forma surdipennis” (see above). The new species clearly differs from T. franzianus by the remarkably different form of aedeagal median lobe which is smaller, more strongly curved behind basal bulb, not bent upwards behind middle, seen laterally, and not widened behind middle on left side, seen dorsally. For differentiation from the newly described species T. aedeagalis sp. n., T. eremita sp. n., and T. sculptipennis sp. n., see the diagnoses of those species below.

Relationships: See remarks in chapter Relationships of T. tilitshoensis Schmidt, 1994 .

Distribution: Fig. 98 . West slope of Sisne Himal, Western Nepal Himalaya . Up to now only known from the north slope of Dolphu Kang pass descent to Mugu Karnali River.

Habitat: Edaphic species of the lower alpine zone; vertical distribution approximately 4100–4300 m.

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 39–51. Aedeagal median lobe with sclerotized portions of internal sac in lateral view (Figs. 39, 40, 42, 43, 45, 47, 49; Figs. 39, 40, 47, 49 in addition with parameres) and in dorsal view (Figs. 41, 44, 46, 48, 50). Fig. 39, Trechus pumoensis Deuve, 1997, paratype. Figs. 40, 41, T. franzianus Mateu & Deuve, 1979, non-type specimen from Dhauli Lake. Fig. 42, T. tilitshoensis Schmidt, 1994, non-type specimen from Gungdang N-slope. Fig. 43, 44, T. muguensis sp. n., paratype (43) and holotype (44). Figs. 45, 46, T. eremita sp. n., paratype. Figs. 47, 48, T. sculptipennis sp. n., paratype. Figs. 49, 50, T. aedeagalis sp. n., paratype. Fig. 51, T. stratiotes 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.