Trechus chiguguanensis, 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 : 478-479

Trechus chiguguanensis sp. n.

( Fig. 22, 25 )

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Material: Holotype: 1(1) ♂, “ China, Sichuan, Shuajingsi ( SSE), E of Chiguguan Pass, H~ 4300 m, 15.07.2000, Belousov I. & Kabak I. leg.” [31º52ʹ51ʹʹN / 102º41ʹ11ʹʹE] ( ZISP) . Paratypes: 37(6) ♂♂, 24(2) ♀♀, collected with holotype ( IZAS, MPU, ZISP, ZSM, BMNH, CAG, CAK, CBK, CDW, CJS, CVZ) ; 7(2) ♂♂, 3♀♀, “ China, Sich- uan, S of Shuajingsi, NNE of Chiguguan Pass , H~ 4200 m, 16.07.2000, Belousov I. & Kabak I. leg.” [31º53ʹ13ʹʹN / 102º40ʹ25ʹʹE] ( CBK) ; 4(1) ♂♂, 1♀, “ China, Sichuan, SE Shuajingsi, SE slope of Chiguguan Pass , 3500 m, 14.07.2000, Belousov I. & Kabak I. leg.” ( CBK) ; 1(1) ♂, “ China, Sichuan, Shuamalukou (10 km S), left bank of Somohe River , 3200 m, 17.07.2000, Belousov I. & Kabak I. leg.” [31º55ʹ33ʹʹN / 102º39ʹ02ʹʹE] ( CBK) .

Description. Body oblong-ovate, nearly parallel-sided in median portion, slightly constricted at pronotal base, subconvex ( Fig. 22). Appendages moderately long, legs stout. Upperside pitchy black to amber reddish, suture, mar-

gins of elytra and occasionally disc of pronotum paler. In pale specimens, disc of elytra and posterior part of head darkest. Legs uniformly yellowish. Antennae reddish yellow.

Head size slightly above average, much paler before clypeal suture than behind, boundary often sharply defined. Eyes average to rather small, subconvex, tempora long and subconvex, scarsely pubescent. Frontal furrows evenly impressed, subangulate, approaching each other in middle; frons between them convex. Supraorbital setae located in lines subparallel or slightly convergent anteriad, posterior seta located far behind posterior margin of eye. Pores of anterior supraorbital seta markedly foveolate, the posterior one slightly foveolate.

Pronotum moderately transverse, subconvex, with maximum width in apical third, moderately constricted toward base. Its sides regularly and broadly arcuate, shallowly and shortly sinuate before hind angles, latter small, sharp or rather blunt. Posterior margin straight medially, obliquely truncate laterally; anterior margin straight. Anterior angles marked but not salient. Lateral groove very narrow, lateral margins gently reflexed. Prebasal transverse impression shallow, vaguely delimited, more distinct laterally, angularly curved in basal foveae, which are shallow and medium-sized. Apical transverse impression rather vague. Discal foveae lacking or small. Anterior marginal seta placed in about anterior third of pronotum, posterior seta at hind angle. Base of pronotum shallowly to moderately rugose. Median line slightly impressed, becoming clearly deeper near base.

Elytra oblong-oval, with broadly arcuate sides, widest near their mid-length. Humeri broadly rounded, prehumeral margin evenly arcuate, posthumeral sinuation indistinct. Elytral apex nearly truncate, each elytron with distinct subapical sinuation. Elytral striation very shallow, only striae 1–3 well developed though stria 3 often shortened anteriorly and posteriorly; striae 5–7 usually barely traceable, all intervals flat, the second interval about twice as wide as interval 1 in their posterior portions. All elytral striae finely punctured. Stria 2 surpassing level of preapical pore, usually joining stria 3 here, latter without distinct connection with stria 4. Due to reduction of striation, striae 5–7 more or less reduced on apical slope and their connections indistinct. Both parascutellar striole and parascutellar pore present. Apical recurrent striole long, deep and straight, only marginally not reaching level of umbilicate pore 8, directed toward stria 7 anteriorly. Apical triangle usually markedly elongate, its inner side approximately parallel to elytral suture. Preapical pore located clearly before anterior end of apical striole, at level between umbilicate pores 7 and 8. Angulo-apical pore usually set closer to exterior pore than to elytral suture. Lateral margins narrowly expanded and reflexed, more widely in posterior part.

Microsculpture well developed over entire body surface, only slightly shallower on disc of pronotum, consisting of isodiametric meshes on head, subisodiamteric meshes on basal and apical portions of pronotum, irregular and transverse meshes on disc of the latter, and markedly transverse meshes on elytra, pronotum without iridescent luster, elytra with faint iridescence.

Fore tibia slightly grooved on exterior surface in its median part; two basal segments of male foretarsi markedly dilated and dentate.

Median lobe of aedeagus ( Fig. 25 ) of medium size, rather slender, especially in distal portion, angularly curved near base, its distal part directed downward and gradually narrowing toward apex, with a small button-like apex in lateral view; subparallel-sided in dorsal view. Lamella rather long. Sagittal lobe of medium size. Parameres rather thick, straight in distal portion, each bearing 4 apical setae. Endophallus armature consisting of two small sclerotized pieces and one poorly sclerotized scaly area located near left wall of median lobe.

Sexual dimorphism. Males differ in smaller head (PW/HW, on average, 1.26 vs. 1.24 in females, significance level p≤0.05) and longer antennomeres (YL/L3, on average, 1.18 vs. 1.23 in females, p≤0.05).

Comparative notes. T. chiguguanensis sp. n. is most similar to T. turnaioides Deuve, 1997 and T. zoigeicola Belousov & Kabak, 2000 in the aedeagus shape, but the endophallus structure is as in other members of the T. kozlovi species group. Among species of this group, T. chiguguanensis sp. n. can be readily distinguished by its rather narrow and convex habitus, elongate elytra with shallower striae, and particularly by the narrow lateral groove of pronotum ( Fig. 22). Additionally, the median lobe of aedeagus differs in the narrow apical portion clearly attenuated downward ( Fig. 25 ).

Distribution. The species is known from two opposite slopes NE of the Chiguguan Pass located on the road Lixian—Barkam (=Maerkam), northern Sichuan.

Bionomics. The species occurs in a wide range of altitudes in both the alpine and upper forest zones, at elevations between 3200 and 4300 m a.s.l. It was found in different humid habitats, mostly under stones near melting snow.

Derivatio nominis. The species epithet refers to the type locality of the species, the Chiguguan Pass.

Figures

FIGURES 23–25. Male genitalia of Trechus spp. n., paratypes: a—lateral view, b—dorsal view. 23–24 —T. qunlaishanicus sp. n.; 25—T. chiguguanensis sp. n.