Trechus mieheorum, 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 : 40-41

Trechus mieheorum sp. n.

( Figs. 54 , 88 )

Type material: Holotype male, with label data “ TIBET South Centr. 18.VII.07, Reting Tsangpo Vall. E Reting, upp. Kiykiy side vall. 4900–5200 m, 30°24’38N 91°41’10E ” ( SMNS) . Paratypes: 1 male, 2 females, with same label data as holotype ( CSCHM) .

Description: Body length: 4–4.5 mm.

Colour: Dorsal surface dark reddish brown, moderately shiny, antennae and legs slightly lightened, palpi yellowish brown.

Microsculpture: Head almost smooth on clypeus and frons, and with distinctly engraved almost isodiametric meshes in frontal furrows and on neck. Pronotum with very faintly engraved meshes on disc which are visible under high magnification only (x100), and with granulate sculpture due to strongly convex surfaces of sculpticells in basal depressions. Surface of elytra with slightly engraved slightly transverse meshes in both sexes.

Head: Average sized, with eyes small and only slightly protruding. Temples as long as eyes, strongly wrinkled to the neck. Frontal furrows deep between the eyes, but distinctly flattened towards hind suborbital seta. Antennae short, 2.5 antennomeres extend beyond the pronotal base. Antennomere III distinctly longer (1/5 to 1/6) than antennomeres II and IV, both the latter are almost alike in length.

Pronotum: Slightly transverse, subcordate, strongly contracted towards base, and with proportions relatively variable: WP/LP = 1.25–1.34, WP/WPB = 1.34–1.36, WP/WH = 1.19–1.30, WE/WP = 1.61–1.68. Surface moderately convex, sides evenly rounded in anterior ¾ and concave in posterior quarter. Hind angles relatively largely developed, almost rectangular or slightly obtuse. Marginal gutter narrow, not or only slightly widened just anterad of laterobasal depressions. Base rectilinear in middle, slightly curved anteriorly at outer fifth. Basal depressions rough due to strongly convex discs of sculpticells of micromeshes and due to wrinkles in middle of base.

Elytra: Oval, broadest a little behind mid-length; proportion WE/LE = WE/LE = 1.50–1.52. Surface convex, not or slightly flattened on disc. Sides rounded with shoulders indistinct. Striae finely and scarcely punctate, inner three striae moderately deep impressed on disc, but flattened or reduced at apex; striae IV and V only faintly impressed, striae VI and VII completely reduced. Three inner intervals slightly convex. Preapical seta is located on second stria and at the beginning of the posterior elytral sixth.

Male genitalia: Aedeagal median lobe relatively small (LE/LA = 3.04–3.06), in lateral view strongly curved throughout. Basal bulb spherically enlarged but with velum narrow. Tip of terminal lamella with a relatively short upward directed hook. The sclerotized portion of the internal sac forms an outer sheet-like fold in the middle of the median lobe which encloses the base of a long spur-like copulatory piece; the latter proceeds towards the ostium and is more strongly sclerotized at its tip.

Etymology: The specific name is dedicated to Sabine and Georg Miehe, Marburg, for their long-time efforts on forest research and forest conservation in Tibet and especially for their kind support of my own studies on the Plateau. Formed as a noun (plural of name) in the genitive case.

Identification: Within the fauna of southern Tibet this species is easily to distinguish by the shape of the aedeagal median lobe and especially by the presence of a long thorny copulatory piece of internal sac at median lobe ostium. In external characters this species is very similar to the above described T. bastropi sp. n., but differs by having the eyes more strongly reduced, frontal furrows of head more distinctly flattened towards hind suborbital setae, basal antennal joints stouter, pronotal sides more strongly concave rounded towards base, hind angles more strongly produced, pronotal base less curved anteriorly towards hind angles and outer elytral striae finer, with striae VI and VII completely reduced.

Relationships: According to the more strongly reduced eyes this new species, along with T. bastropi sp. n. and T. hodeberti Deuve, 1997 , seems to form a separate evolutionary lineage within the T. dacatraianus group. Due to the presumed sister species relationship of both the latter species as mentioned above, T. mieheorum sp. n. could be the more basal branch of this evolutionary lineage.

Distribution: Fig. 99 . Currently only known from the source area of the Kiykiy brook on north ascent of Reting Tsangpo Valley, approximately 100 km northeast of Lhasa.

Habitat: Higher alpine zone. The species was found under big stones on the top of an old moraine at an altitude of 5200 m.

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.