Trechus gemaensis, Belousov & Kabak, 2020

Belousov, Igor A. & Kabak, Ilya I., 2020, New Trechus species of the kozlovi group from Sichuan (Coleoptera: Carabidae), Zootaxa 4786 (4), pp. 451-484 : 456-459

Trechus gemaensis sp. n.

( Figs 5, 6–7 )

urn:lsid:zoobank.org:act:FBC18AE4-6AB7-4530-B042-964B63523E43

Type material: Holotype: 1(1) ♂, “ China, C. Sichuan, E Danba, SE Mt Gema, bas. Hanniuhe River, N Chengducun Village , 30º52´41´´N / 102º04´22´´ E, H= 4615 m, 15.08.2004, Belousov I. & Kabak I. leg.” ( ZISP) . Paratypes: 8(8) ♂♂, 7(1) ♀♀, collected with holotype ( BMNH, ZSM, MPU, CAG, CBK) .

Description. Body elongate-oval, moderately constricted at level of pronotum base, subconvex, depressed on disc of elytra and along their suture ( Fig. 5). Appendages of medium length. Upperside dark brown; base, anterior part and margins of pronotum, suture and margins of elytra usually reddish. Legs uniformly yellowish brown. Head with darker disk and paler reddish anterior portion, boundary between dark and pale portions located either near mid-length of clypeus or along clypeal suture (as in Fig. 5). Antennae vaguely obscured from segments 4–5, more rarely from segment 3. Maxillary palpi slightly obscured except for their last segment.

Head slightly larger than average (for members of the species group), flattened on disk, eyes medium-sized and rather convex, tempora long and slightly convex, very sparsely and shortly pubescent. Frontal furrows regularly impressed, subangulate and approaching in their middle portions. Supraorbital setae located in lines parallel to body axis, posterior seta far behind posterior margin of eye. Anterior setiferous pore markedly foveolate, posterior one shallowly foveolate.

Pronotum plane, subcordate, distinctly constricted at base, with maximum width in apical third. Its sides broadly arcuate in anterior part, with long and rather shallow sinuation before hind angles, the latter not large, subrectangular, acute or subacute apically, occasionally slightly produced outwards. Posterior margin straight or slightly oblique at sides; anterior margin straight to concave.Anterior angles rounded and barely prominent. Lateral margins moderately expanded, slightly reflexed, lateral groove widened posteriad. Prebasal transverse impression deep but vaguely delimited, often consisting of a few longitudinal foveae, its lateral portions bent near basal foveae. The latter are large and deep, adjoining lateral groove. Apical transverse impression distinct laterally, becoming shallower medially. Anterior marginal seta located in anterior third of pronotum, posterior one at hind angle. Basal surface of pronotum coarsely longitudinally rugose. Median line faintly impressed, deepest near basal margin, barely surpassing the preapical transverse impression anteriad.

Elytra oblong-oval, rather wide, with sides evenly and slightly arcuate, markedly flattened on disk, widest after their mid-length. Humeri marked, though broadly rounded, elytra wider at level of preapical sinuation than at humeral level. Each elytron slightly sinuate at level of umbilicate pore 8 and separately rounded at apex. Elytral striation moderately deep, striae rather regular, the outers shallower, though even stria 7 visible in its median portion. Occasionally, some striae slightly waved. Inner interspaces, at most, subconvex, outer ones flat. All interspaces subequal in width except for interspace 1, which is evenly narrow, and interspace 2, which is much wider posteriorly than other interspaces. Elytral striae finely punctured. Most common type of apical striation: ((2x3)x4)((5x6)x7)xAS but this pattern is not stable, since apical striole can join any of striae 5–7. Apical striole evenly curved, deep in its posterior part, gradually shallowing and straightening in anterior part. Parascutellar striole distinct. Apical triangle markedly elongate, its inner side nearly parallel to body axis. Angulo-apical pore twice as far from preapical pore as from exterior one. Preapical pore usually located on interspace 3 at level of anterior termination of carinula near apical striole, much more rarely in stria 2. In the latter case, interspace 2 markedly widened in posterior part. Lateral groove of elytra average, margins slightly reflexed. Basal portion of the lateral border directed toward anterior termination of stria 4.

Microsculpture markedly developed over entire body surface, consisting of isodiametric meshes on head, slightly transverse meshes on disc of pronotum, except for nearly isodiametric meshes on its base and near preapical impression and consisting of markedly transverse meshes on elytra. All upper surface matt, micropunctured, glabrous.

Front tibiae without trace of longitudinal groove, glabrous on their anterior surface. Two basal segments of male anterior tarsi markedly dilated, each inwardly dentate.

Median lobe of aedeagus ( Figs 6–7 ) angularly bent at basal portion, with maximum width in apical third. Ventral margin distinctly sinuate in apical third of aedeagus, convex in its median part. Apical portion straight, without distinct button-like dilation or apical disc. Viewed dorsally, median lobe rather thick, nearly parallel-sided, slightly narrowed toward the apex, which is broadly rounded. Basal orifice moderately emarginate. Sagittal lobe of medium size. Parameres rather long, clearly narrowing distally, obliquely truncate and rounded apically, each bearing 4 apical setae. Left paramere clearly longer, with a well-developed ventral apophysis. Endophallus armature consisting of two rather large and moderately sclerotized pieces located in middle part of median lobe. Proximal piece larger, subtriangular or trapezoid in lateral view, located near left wall of median lobe. Distal one located largely in horizontal plane and covered with a sparse scaly mesh from above.

Sexual dimorphism. No significant differences between sexes.

Comparative notes. This species is closely related to the sympatric T. suopoensis sp. n. described above. Externally it differs only in its larger size (body length, on average, 3.25 mm vs. 3.07 mm in T. suopoensis sp. n., p≤0.001), pronotum with wider lateral groove and front angles more salient and less broadly rounded (see from in front and above), elytra wider (EW/PW, on average, 1.65 vs. 1.60, p≤0.001; EW/HW, on average, 2.03 vs. 1.98, p≤0.01) and less convex (EL/BH, on average, 2.69 vs. 2.56 in T. suopoensis sp. n., p≤0.001, p-values are given from the parametric t -test), with maximum width clearly behind their mid-length. The aedeagus of T. gemaensis sp. n. is larger, much thicker, its ventral margin is clearly convex in median portion, the copulatory pieces are also much larger and more heavily sclerotized ( Figs 6–7 vs. Figs 2–4 ).

Distribution. T. gemaensis sp. n. is found on the southern slopes of Mount Gema, east of Suopo Village (Sichuan) where it co-occurs with T. supoensis sp. n.

Bionomics. The species was collected in alpine meadows at an elevation of 4615 m.

Derivatio nominis. The species epithet refers to the toponym “Gema”, the mount where the species was found.

Figures

FIGURES 6–7. Male genitalia of Trechus gemaensis sp. n., paratypes: a—lateral view, b—dorsal view, c—dorsal view at a right angle to apical lamella.

FIGURES 2–4. Male genitalia of Trechus suopoensis sp. n., paratypes: a—lateral view, b—dorsal view, c—dorsal view at a right angle to apical lamella.