Trechus stratiotes, 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 : 58-60

Trechus stratiotes sp. n.

( Figs. 51 , 84 )

Type material: Holotype male, with label data “ NEPAL Prov. Karnali Distr. Humla , 16 km W Simikot, 3 km NW Sankha La, 4300–4800 m, 29°57’18’’N 81°39’30’’E, HF 29.– 30.06.2001, leg. A. Kopetz, stone-debris & alpine mats” ( NME).

Paratypes: 46 males, 33 females, with same label data as holotype ( CKOP, CSCHM, NME) ; 5 males, 1 female, with same label data, but: 4000–4300 m ( CKOP) ; 53 males, 26 females, with same label data, but: 4250–4600 m, leg. M. Hartmann ( CSCHM, NME) ; 5 males, 2 females, with same label data, but: 4100–4500 m, leg. A. Weigel ( CSCHM, CWG) ; 9 males, 7 females, with same label data, but: 4700–4800 m, snow fields, 29°56N 81°39E, 30.VI.2001, leg. E. Grill & A. Weigel ( CGR, CWG) ; 1 male, 1 female, ditto, but: 3–4 km NW Sankha La , 4250 m, alpine meadows, pasture, 29°57’18N 81°39’30E, 29.VI.2001, leg. M. Hartmann ( NME) ; 8 males, 4 females, ditto, but: 2 km NW Sankha La , 4250–4950 m, snow fields and alpine mats, 29°56’39N 81°39’02E, 29.VI.2001, leg. E. Grill ( CGR) ; 7 males, 5 females, Nepal, Prov. Seti, Distr. Bajura, 10 km SE Chala, vor [before] Sankha La , 4200–4400 m, 29°57’1N 81°39’3E, 30.VI.2001, leg. J. Weipert ( CWP) ; 16 males, 6 females, ditto, but: Umg. [environment] Sankha La , 4400–4800 m, 29°56’4N 81°40E, 1.VII.2001, leg. J. Weipert ( CWP) ; 16 males, 3 females, ditto, but: Umg. Lager [environment camp] S Sankha La , 4600–4900 m, 29°56’2N 81°40’1E, 2.VII.2001, leg. J. Weipert ( CWP) ; 1 male, 1 female, Nepal, Prov. Seti, Distr. Bajura, 15 km W Simikot, Dudh Lekh / Dudh Tal , 4650–4800 m, 29°56’09N 81°40’32E, stonedebris, glacier lakeside, 1.VII.2001, leg. A. Kopetz ( CKOP) ; 5 males, 3 females, ditto, but: 4700 m, snow fields and glacier lakeside, 1.VII.2001, leg. E. Grill ( CGR, CSCHM) ; 3 males, 1 female, ditto, but: 4650 m, glacier lakeside, 2.VII.2001, leg. A. Kopetz ( CKOP) ; 6 males, 2 females, ditto, but: 4600–4900 m, stonedebris and glacier lakeside, 2.VII.2001, leg. M. Hartmann ( CSCHM, NME) ; 1 male, Nepal, Prov. Seti, Distr. Bajura, 18 km W Simikot, Sankha La – Kuwadi Khola , 4600– 4000 m, mountain meadows and pastures, 29°54’40N 81°38’49E, 3.VII.2007, leg. A. Kopetz ( CKOP) ; 1 male, 1 female, ditto, but: 19 km WSW Simikot, Kuwadi Khola valley , 3500–3700 m, mountain meadows and riverside, 29°53’10N 81°38’40E, 4.VII.2001, leg. M. Hartmann ( NME) ; 5 males, 3 females, ditto, but: 19 km W Simikot, Kuwadi Khola , 3500 m, river side, 29°53’14N 81°38’40E, 4.VII.2001, leg. A. Weigel ( CSCHM, CWG) ; 5 males, 3 females, ditto, but: riverbank, coniferous-birch-forest, 4–5.VII.2001, leg. A. Kopetz ( CKOP) .

Description: Body length: 3.2–3.7 mm.

Colour: Dorsal surface dark brown, shiny; pronotum in some specimens reddish brown lightened, palpi, legs and antennae yellowish brown, antennal segments IV–XI or V–XI somewhat darkened in most specimens.

Microsculpture: Surface of head with moderately engraved isodiametric meshes throughout (x40–x50). Pronotum with more faintly engraved slightly transverse meshes on disc (x80) but more deeply impressed almost isodiametric meshes in basal depressions. Elytral disc with faintly engraved narrow and more strongly transverse meshes (x100).

Head: Broad, with eyes small and slightly protruding; temples approximately ¾–4/5 of length of eyes and strongly wrinkled to the neck. Antennae relatively short, 2–2.5 antennomeres extend beyond the pronotal base. Antennomere II nearly as long as antennomere III, the latter is distinctly (approximately 4/5) longer than antennomere IV.

Pronotum: Moderately large, transverse, strongly contracted towards base; proportions: WP/LP = 1.34–1.40, WP/WPB = 1.40–1.43, WP/WH = 1.24–1.29, WE/WP = 1.45–1.50. Surface strongly convex. Sides convexly rounded in anterior 2/3 and straight towards hind angles, the latter pointed. Marginal gutter moderately narrow, slightly widened anterad of laterobasal depressions. Base rectilinear in middle, slightly shifted posteriorly towards sides. Basal depressions with fine longitudinal wrinkles both sides of pronotal middle.

Elytra: Sub-oval, relatively broad at shoulders, hardly convex at the end of the anterior elytral third, broadest little behind mid-length; proportion WE/LE = 1.45–1.53. Surface strongly convex, not flattened on disc. Shoulders rounded, but slightly distinct. Striae punctate, first stria fully deep impressed, second and third striae also deeply impressed but reduced at base, fourth and fifth stria distinctly shallower, sixth stria hardly visible, stria VII completely reduced in anterior 2/3 and faintly impressed in posterior third. Intervals I–III (- IV) strongly convex. Location of preapical seta somewhat variable, usually marking the fusion point of the second and third striae, which in most specimens is located at the beginning of the last seventh or eighth of the elyton, but in some specimens located little more posteriorly (up to the beginning of the last ninth).

Male genitalia: Aedeagal median lobe moderately short (LE/LA = 2.92–3.03), in lateral view strongly curved in basal 3/4, but straight towards apex; terminal lamella moderately short, simply narrowed seen dorsally. Copulatory piece of internal sac elongated, approximately 2/3 of length of median lobe, lance-like in anterior half, slightly curved throughout.

Etymology: The specific name is derived from the Latinized ancient Greek word “stratiotes” [strat-ee-o’- tace, a (common) soldier] and refers to the lance-like form of the sclerotized internal sac portion that give the new species an armed appearance; noun in apposition.

Identification: Within the Trechus fauna of Tibet and Himalaya this new species is easily to recognize by its unique male genitalia characters, especially by the external shape of the aedeagal median lobe, and by the lance-like form of the large copulatory piece. It differs strikingly from all other Trechus species of the Western Nepal Himalaya and adjacent mountainous regions by lacking the veliform appendix of the median lobe basal bulb.

Relationships: From a taxonomic point of view T. stratiotes sp. n. seems widely isolated within the Trechus fauna of Western Nepal and the ancient Western Himalaya as well. Within this region two diverse species groups occur: The T. franzianus group as described in this paper (see above), of which one species ( T. sculptipennis sp. n.) is sympatric with T. stratiotes sp. n., and the T. quadristriatus group sensu lato (see remarks on the T. thibetanus group, above). Both these groups represent quite different evolutionary lines within the genus Trechus . Moreover, no relatives of T. stratiotes sp. n. could hitherto be identified within the fauna of the Himalaya or the fauna of the Tibetan plateau. The male genitalia characters of the new species are so striking in several respects (external form of aedeagus with complete reduction of basal bulb appendix, structures of internal sac sclerotized portion), that a separate evolution after split off from a more basal Trechus line is likely. Although several similarities in external shape and in microsculpture of body surface could suggest closer relationships of T. stratiotes sp. n. to the Central Himalayan species group of T. tosioi Uéno, 1972 (see also discussion in chapter Relationships of T. rolwalingense sp. n., below), however, at the actual state of knowledge, none of these characters are reliable synapomorphies.

Distribution and geographical variation: Fig. 98 . The nominotypical form is distributed in the vicinity of pass Sankha La and on slopes north of the pass down to the Kuwadi Khola valley on north eastern macro slope of Saipal Himal, Far Western Nepal. A form somewhat differing in external morphology was found southeast of the Sankha La pass and will be described as a separate subspecies below.

Habitat: Presumably a species of the subalpine and lower alpine zones, with its highest occurrences on alpine meadows at about 4700–4800 m, and the lowest findings at an altitude of 3500 m on riverbanks in the higher montane zone.

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.