Trechus rolwalingensis, 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 : 61-62

Trechus rolwalingensis sp. n.

( Figs. 10 , 63, 64 , 83 )

Type material: Holotype male, with label data “ NEPAL Rolwaling Vall., Yarlung Ri base camp 4600–4800 m, 16.– 18.9.1999 lg. Schmidt” ( SMNS).

Paratypes: 18 males, 11 females, with same label data as holotype ( BMNH, CKAB, CSCHM, CWR, MNHN, SMNS) ; 1 male, Nepal, Rolwaling Valley , Na vill. [village] 4000–4100 m, 16.IX.1999, leg. J. Schmidt ( CSCHM) ; 13 males, 16 females, ditto, but: Na to Yarlung Ri base camp 4200–4900 m, 23.V.2000, leg. J. Schmidt ( CSCHM) ; 1 female, ditto, but: Na to Tso Rolpa lake, 4200–4400 m, 21.V.2000, leg. J. Schmidt ( CSCHM) ; 2 males, 1 female, ditto, but: Tsho Rolpa , 4400 m, 21.V.2000, leg. J. Schmidt ( CSCHM) .

Description: Body length: 3.2–3.7 mm.

Colour: Dorsal surface dark brown, shiny; palpi, scapus, pedicellus, anterior half of antennal segment III and legs light brown.

Microsculpture: Head with moderately engraved isodiametric meshes on supraorbital area, neck and in frontal furrows (x40–50). 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 2/3–3/4 of length of eyes and strongly wrinkled to the neck. Antennae short, 1.5–2 antennomeres extend beyond the pronotal base. Antennomere III is as long as or slightly longer than antennomere II, antennomere IV is slightly shorter (5/6–6/7) as antennomere III.

Pronotum: Large and transverse, subcordate, strongly contracted towards base; proportions: WP/LP = 1.31–1.39, WP/WPB = 1.36–1.42, WP/WH = 1.31–1.38, WE/WP = 1.53–1.59. Surface strongly convex. Sides convexly rounded in anterior 3/4 and curtly concave anterad of hind angles; the latter small but rectangular, seldom slightly obtuse. Marginal gutter moderately narrow, slightly widened anterad of laterobasal depressions. Base rectilinear or weakly convex, slightly curved anteriorly at outer fifth; basal depressions with fine longitudinal wrinkles both sides of pronotal middle.

Elytra: Broad oval, broadest little behind mid-length, with proportion WE/LE = 1.36–1.41. Surface strongly convex, not flattened on disc. Shoulders rounded, indistinct. Striae impunctate, first and second striae fully deep impressed, third striae somewhat shallower and reduced at base and extreme apex, fourth stria indistinct and striae V–VII completely reduced. Second and third interval strongly convex. Preapical seta is located in the third interval often close to the second stria and, in most specimens, at the beginning of the posterior elytral seventh, but in some specimens located slightly anteriorly (up to the beginning of the posterior fifth).

Male genitalia: Aedeagal median lobe moderately short (LE/LA = 2.87–3.00), with ventral side almost straight in middle, and with terminal lamella slightly bent downwards; the latter shortly bill-like in lateral and in dorsal view. Copulatory piece of internal sac relatively complex as shown in Fig. 63 .

Etymology: The specific name is derived from the type locality, the Rolwaling Valley (adjective).

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, by the strongly sclerotized median lobe ostium, and the extraordinary form of the copulatory piece.

Relationships: Due to the large and more strongly transverse pronotum with deep laterobasal foveae, the broader oval elytra with more strongly reduced lateral striae, and due to the general shape of the copulatory piece with broader basal portion and thorn-like or needle-like distal portion, T. rolwalingensis sp. n. seems to be member of the species diverse Central Himalayan group of T. tosioi Uéno, 1972 (which, after a preliminary study, includes T. breuningi Morvan, 1972 , T. gorkhai Schmidt, 1998 , T. gurungi Schmidt, 1998 , T. lamjunensis Schmidt, 1994 , T. namunlaensis Schmidt, 1998 , and T. tamangi Schmidt, 1998 ). However, the male genitalia characters of the new species are so striking that a more detailed character study of the Himalayan Trechus fauna is needed before further conclusions can be drawn.

Distribution and geographical variation: Fig. 98 . High Himalaya of Central Nepal: The nominotypical form is distributed in the upper Rolwaling Valley between Solu Khumbu Massif in the South and Rolwaling Himal in the North. A form somewhat differing in external morphology was found in the western Rolwaling Valley and will be described as a separate subspecies below.

Habitat: Vertical distribution approximately 3600–4600 m, from the cloud forests of the higher parts of the high montane zone (“Obere Nebelwaldstufe” sensu Miehe, 1991) up to the meadows of the lower alpine zone. In the cloud forests the specimens were sifted from leaf litter, and in the subalpine and alpine zones they were found under stones on humid slopes.

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 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 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.