Trechus bianericus, 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 : 459-460

Trechus bianericus sp. n.

( Figs 8, 9–11 )

urn:lsid:zoobank.org:act:8B551745-60FB-41C7-AD17-4AB30C5C2720

Type material: Holotype: 1(1) ♂, “ China, C. Sichuan, WNW of Danba, 8.8 km S of Bianer (= Bianr ), 30º58´46´´N / 101º31´52´´ E, H~ 3770 m, 20.08.2004, Belousov I. & Kabak I. leg.” ( ZISP) . Paratypes 30(8) ♂♂, 17♀♀, collected with holotype ( IZAS, MPU, BMNH, ZISP, ZSM, CAG, CAK, CBK, CDW, CJS, CVZ); 1(1) ♂, China, C. Sichuan, WNW of Danba , 7.2 km S of Bianer (=Bianr), 30º59´41´´N / 101º31´50´´ E, H~ 3530 m, 20.08.2004, Belousov I. & Kabak I. leg.” ( CBK) .

Description. Species of small size, body broad and convex, ovate, moderately constricted at base of pronotum ( Fig. 8). Appendages rather short and robust, especially femora. Upperside reddish brown, with darker head and disc of elytra.Anterior part of head, disc of pronotum, suture and margins of elytra reddish. Legs and antennae uniformly reddish yellow.

Head rather large, eyes small and subconvex, tempora long and markedly convex, without distinct pubescence. Frontal furrows deeply impressed, subangulate, approaching each other in middle. Supraorbital setae located in lines subparallel to body axis or slightly convergent posteriad, posterior seta located far behind posterior margin of eye. Pores of both anterior and posterior setae foveolate, though posterior one less markedly. Tooth on right mandible tridentate, with rather long basal margin.

Pronotum convex, markedly transverse, with maximum width in apical third. Discal foveae absent. Sides broadly arcuate anteriorly, with a shallow sinuation before hind angles, the latter small, obtusangular or subrectangular, pointed at apices. Posterior margin convex medially, slightly oblique laterally, anterior margin straight or barely concave. Anterior angles rounded, not clearly produced anteriorly. Lateral margins bordered and moderately re- flexed, lateral groove of average width, dilated posteriorly. Prebasal transverse impression shallow, curved in basal foveae, the latter of average size and depth. Apical transverse impression shallow, perceptible mostly laterally. Anterior marginal seta located in about anterior third of pronotum but distinctly behind anterior quarter of pronotal length, posterior seta at hind angle. Base of pronotum sparsely rugose medially. Median line slightly impressed, becoming deeper near prebasal transverse impression and basal margin.

Elytra broad, oval, widest near their mid-length or slightly behind, wider at level of preapical sinuation than at humeral area, with arcuate sides. Humeri prominent, though broadly rounded, prehumeral margin evenly arcuate, posthumeral sinuation barely distinguishable. Elytral apex narrowly rounded, with slight subapical sinuation at level slightly behind umbilicate pore 8. Elytral striation shallow but rather regular, even stria 7 traceable for most of its length. 3–4 inner stria well impressed. Stria 8 vague between humeral and median groups of umbilicate series. Inner interspaces subconvex, outer ones flat. Interspace 1 only marginally narrower in its posterior half than other interspaces and nearly as wide as the second in its anterior half. All elytral striae finely punctured. Striation on apical slope as follows: stria 3 joining stria 4 and then stria 2 posteriorly, striae 5 and 6 joining each other at level between umbilicate pores 6 and 7, then directed to but not connected with apical striole; stria 7 joining apical striole posteriorly. Parascutellar striole very short, not joining any striae posteriorly. Apical striole short, evenly curved, apical carina slightly salient. Apical triangle markedly elongate, its inner side either parallel to body axis or slightly divergent posteriorly. Preapical pore located at level slightly anteriad of anterior termination of apical striole. Lateral groove of average width, somewhat expanded in humeral area.

Microsculpture distinct over entire body surface, though much shallower on disc of elytra, consisting of isodiametric meshes on head, irregular and slightly transverse meshes on disc of pronotum, and transverse anastomosing lines on elytra, the surface of the latter slightly iridescent.

Anterior tarsi of male with 2 basal segments markedly dilated, protibiae with exterior surface flattened in both sexes but without distinct groove.

Aedeagus, in lateral view ( Figs 9–11 ), rather large, with maximum width near middle, angularly bent at basal portion, its ventral margin nearly straight, concave before apex; apical portion directed gently downward, with a small button-like apex. In dorsal view, its tube subequal in width for most of its length, apical lamella clearly narrower, with nearly parallel sides; its apex widely rounded. Sagittal lobe small to average. Basal orifice slightly concave. Parameres relatively thick, nearly straight in apical half, truncate or widely rounded apically; left paramere clearly longer, with a well-developed ventral apophysis; each paramere bearing four apical setae, sometimes grouped into two pairs. Endophallus armature consists of two poorly sclerotized pieces, the proximal piece, in lateral view, looks like three oblong subparallel folds, and distal one, comprising distinct scaly patch, is located in horizontal plane closely to dorsal wall, with two vertical folds in lateral view.

Sexual dimorphism. Males differ in narrower pronotum (PW/PL, on average, 1.36 vs. 1.38 in females) longer elytra (EL/EW, on average, 1.31 vs. 1.28 in females, for both the above ratios, p≤0.01) and narrower head and shorter apical margin of pronotum (the two last characters are nearly always correlated in Trechus species, EW/HW, on average, 1.98 vs. 1.96 in females, PB/PA, on average, 1.02 vs. 0.99 in females, for both ratios, p≤0.05).

Comparative notes. T. bianericus sp. n. resembles the species related to T. gansuensis Deuve & Quéinnec, 1993 and T. xiei Deuve, 1992 in the following external characters: rather small size, robust oval facies, small and convex eyes, long and convex tempora, transverse pronotum with basal margin clearly oblique laterally, more posterior position of the preapical setiferous pore and shallower microsculpture of elytra. On the other hand, the structure of the male genitalia shows certain similarities with some species of the kozlovi -group, particularly with the two species described above ( T. suopoensis sp. n. and T. gemaensis sp. n.) and one more species ( T. maoniu sp. n.) described below ( Figs 9–11 vs. Figs 2–4 , 6–7 and 13–14 ). Rather poor sclerotization of the endophallus armature does not allow reliable interpretation of its structure and, therefore, the assignment of T. bianericus sp. n. to the kozlovi species group needs further evidence.

Distribution. T. bianericus sp. n. was found on the nortwestern slopes of the mountain massif located south of Bianer Village (WNW of Danba City, Sichuan).

Bionomics. The species occurs in the upper belt of the forest zone near timberline. It was collected by sifting from forest litter at elevations from 3530 to 3770 m. At higher altitudes, in the alpine zone, T. bianericus sp. n. is replaced by T. maoniu sp. n.

Derivatio nominis. The species is named after the toponym “Bianer (=Bianr)”, a small village located not far from Danba City.

Figures

FIGURES 9–11. Male genitalia of Trechus bianericus sp. n., paratypes: a—lateral view, b—dorsal view.

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.

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 13–14. Male genitalia of Trechus maoniu sp. n., paratypes: a—lateral view, b—dorsal view, c—dorsal view at a right angle to apical lamella.