Trechus cuspis, 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 : 468-477

Trechus cuspis sp. n.

( Fig. 17, 20 )

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Type material: Holotype: 1(1) ♂, “ China, NW Sichuan, NW of Lixian , S slope of Mt. „5200“, 4400–4800 m, 28.07.2002, Belousov I. & Kabak I. leg.” [31º37´30´´N / 102º59´30´´ E] ( ZISP) . Paratypes: 1(1) ♂♂, 2(2) ♀♀, col- lected with holotype ( CBK) .

Description. Body elongate-oval, moderately constricted at base of pronotum, sides of elytra broadly arcuate, nearly parallel in median portion, dorsum slightly convex ( Fig. 17). Appendages moderately long and rather thick. Upperside pitchy black to reddish brown, often disc of pronotum, suture and margins of elytra reddish. Legs uniformly reddish brown, rather pale. Antennae obscured in median portion from the apical part of segment 5. Head before clypeal suture vaguely paler, reddish.

Head average, eyes medium-sized and rather convex, tempora comparatively long and slightly convex, with a few very short hairs. Frontal furrows evenly impressed, subangulate or arcuate, approaching each other in middle, deepest behind their mid-length. Supraorbital setae located in lines slightly convergent anteriad, posterior seta far behind posterior margin of eye. Pores of both anterior and posterior setae foveolate, though posterior one less markedly.

Pronotum convex, subcordate, moderately constricted at base, with maximum width in apical third. Its sides broadly arcuate in anterior part, moderately sinuate before hind angles, the latter rather large and acute, slightly produced outwards. Posterior margin straight, slightly emarginate at sides; anterior margin straight. Anterior angles marked and rounded. Lateral margins narrowly reflexed, lateral groove of average width, slightly expanded posteriorly. Prebasal transverse impression parallel to basal margin, markedly curved near basal foveae, not sharply engraved. Basal foveae large and deep. Apical transverse impression distinct laterally, becoming shallower or even completely effaced medially. Anterior marginal seta placed in about anterior third of pronotum, posterior seta at hind angle. Base of pronotum longitudinally rugose. Median line well impressed, deepest near its base, not reaching anterior margin.

Elytra oblong-oval, with sides evenly and broadly arcuate, which are nearly parallel in middle part, widest near or slightly behind their mid-length. Humeri distinct, but rounded. Elytral apex widely rounded, each elytron with distinct preapical sinuation. Striation of elytra rather complete but shallow: striae 1–4 well impressed and entire, others becoming shallower toward sides. All elytral striae faintly punctured. Stria 2 surpassing level of preapical pore and usually reaching apical border of elytron, normally without distinct connection with stria 3; latter joining stria 4 approximately at or far before level of anterior end of apical striole; striae 5 and 6 joining each other far before elytral apex, near level of median group of umbilicate series; stria 7 without distinct connection with apical striole. Parascutellar striole long and well engraved, Parascutellar pore present. Apical recurrent striole deep, straight or slightly curved, rather long, though not reaching level of umbilicate pore 7 anteriorly, markedly divergent from suture anteriad, externally bordered by a well-developed carina. Apical triangle very long, angulo-apical pore more distant from elytral suture than from exterior pore. Lateral groove rather narrow, margins moderately reflexed.

Microsculpture rather coarse, especially in females; well developed over entire body surface, consisting of isodiametric meshes on head, irregular and slightly transverse meshes on disc of pronotum, nearly isodiametric meshes on its base, and markedly transverse meshes on elytra, latter without iridescent luster on their surface.

Fore tibiae slightly flattened on their exterior surface in middle part, with a few short hairs on anterior surface near inner apex of tibia. In male, two proximal segments of protarsi markedly dilated and inwardly dentate, both being clearly transverse.

Aedeagus with median lobe of medium length, subcylindrical, though clearly dilated in apical third, moderately bent at base, with a distinct apical disc ( Fig. 20 ). In dorsal view, median lobe rather thick, subparallel-sided. Preputial field rather large, asymmetrical, always surpassing mid-length of median lobe but not reaching the basal bulb. Ventral surface with a slightly defined carina. Apical lamella well defined, wide, of triangular shape and rounded at apex in dorsal view. Sagittal lobe of medium to small size. Parameres relatively long and slender, straight in distal half, left paramere clearly longer, with a well-developed ventral apophysis; each paramere bearing 4 apical setae. Endophallus armature Z-shaped in dorsal view; consisting of two slightly sclerotized pieces: proximal one very narrow, strip-like, located near mid-length of median lobe; distal piece long, obliquely placed, with a distinct acute processus directed to right wall of aedeagal tube, scaly patch barely distinguishable in distal quarter of aedeagus near its dorsal wall.

Comparative notes. T. cuspis sp. n. is most closely related to the allopatric T. shangensis sp. n. but differs in having the more parallel-sided and less convex habitus, the pronotal base less markedly oblique laterally, and more distinct microsculpture, especially in females. Morphometrically (significance level is based on the t -criterion), T. cuspis sp. n. is, on average, larger (average body length 3.42 mm vs. 3.27 mm in T. shangensis sp. n.) and less convex (ratio EL/BH, on average, 2.62 vs. 2.42 in T. shangensis sp. n.), has a smaller and narrower pronotum (ratios: EW/PW, on average, 1.60 vs. 1.53, EL/PL 2.82 vs. 2.72, PW/HW 1.24 vs. 1.27 in T. shangensis sp. n.); longer antennomere 3 (ratio L3/L2 is, on average, 1.18 vs. 1.11 in T. shangensis sp. n.); larger eyes (YL/TL 1.81 vs. 1.62 in T. shangensis sp. n.); and umbilicate pores 1, 3 and 4 shifted posteriad. The male genitalia differ from those of both T. shangensis and T. mengensis spp. n. in the shape of the median lobe and particularly in a Z-like shape of the endophallus armature in dorsal view ( Fig. 20 vs. Figs 18–19 ). Additionally, the new species differs from T. mengensis sp. n. in the smaller size (average body length 3.42 mm vs. 3.63 mm in T. mengensis sp. n.) elytral striae more distinctly punctured, narrower elytra (average ratios: EL/EW 1.38 vs. 1.34, EW/PW 1.60 vs. 1.65, EW/HW 1.98 vs. 2.06), stouter antennae and legs (average ratios: L3/W3 2.02 vs. 2.23; TiL/TaL 1.33 vs. 1.43; EL/TiL 2.23 vs. 2.16 in T. mengensis sp. n.), larger eyes (average ratios: YL/TL 1.81 vs. 1.62; YL/L3 1.22 vs. 1.15), and umbilicate pores 5 slightly shifted anteriad (differences of these species based on the Mann—Whitney criterion are shown in Table 3).

Distribution. T. cuspis sp. n. is only known from the southern slopes of Mt. “5200”, NW of Lixian City, Lixian County, N Sichuan.

Bionomics. The species was found under stones in the alpine zone at rather high elevations between 4400 and 4800 m.

Derivatio nominis. The species epithet is derived from the Latin word “cuspis” meaning sting or spear referring to a particular shape of the endophallus armature ( Fig. 20b ).

Figures

FIGURES 18–20. Male genitalia of Trechus spp. n., paratypes: a—lateral view, b—dorsal view. 18—T. shangensis sp. n.; 19—T. mengensis sp. n.; 20—T. cuspis sp. n.