Trechus aghiazicus Belousov & Kabak, 2019

Belousov, Igor A. & Kabak, Ilya I., 2019, New species of the genus Trechus Clairville, 1806 from the Chinese Tien Shan (Coleoptera: Carabidae), Zootaxa 4679 (1), pp. 47-68 : 58-64

Trechus aghiazicus Belousov & Kabak , sp. n.

( Figs. 11 , 15–17 )

Type material: Holotype: 1(1) ♂, “ China, Xinjiang, W of Narat Mt. R, sources of right tributary of Tshong-Muyuny River near Biyke Pass , 42º40´20´´ N / 81º20´50´´ E— 42º38´40´´ N / 81º21´30´´ E, 3100–3800 m, 26.07.2003, Kabak I. leg.” ( ZISP) . Paratypes: 42(6) ♂♂, 13♀♀, collected with holotype ( IZAS, MPU, BMNH, SMNS, ZISP, ZSM, CAG, CAK, CBK, CDW, CJS, CVZ) ; 83(8) ♂♂, 38 ♀♀, “ China, Xinjiang, N slope of Khalyktau Mt. Range, Aksay River (left tributary of Aghiaz River ), 42º30´40´´ N / 81º18´30´´ E— 42º30´00´´ N / 81º18´25´´ E, 3500–3600 m, 29.07.2003, Kabak I. leg.” ( BMNH, SMNS, ZSM, CBK) ; 6(6) ♂♂, 1♀, “ China, Xinjiang, N slope of Khalyktau Mt. Range, Tshon-Aidak SSE Tekes , 42º32´47´´ N / 82º05´56´´ E— 42º32´51´´ N / 82º05´36´´ E, 3330–3550 m, 11.07.2012, Kabak I. leg.” ( CBK) ; 23(8) ♂♂, 5♀♀, “ China, Xinjiang, N slope of Narat Mt. R., SSW of Tekes, Kok- terek basin, Buryl Riv. , 3145 m, 28.07.2009, 42º48´06´´ N / 81º41´20´´ E, Kabak I. leg.” ( CBK) . 14(5) ♂♂, 4♀♀, “ CH, Xinjiang, Koeksu Vall., Dunsala Riv. , S of Tekes, 42º41´43´´ N / 81º50´39´´ E, 3590 m, 8.07.2012, Kabak I.I. leg.” ( CBK) ; 2(2) ♂♂, “ CH, Xinjiang, Koeksu Vall., Dunsala Riv. , S of Tekes, 42º42´42´´ N / 81º51´12´´ E, H= 2655 m, 7.07.2012, Kabak I.I. leg.” ( CBK) .

Description. Body slightly elongate, subparallel-sided, moderately constricted at pronotal base, subconvex, depressed on disc ( Fig. 11 ). Appendages rather short. Upper-side uniformly brownish testaceous, occasionally with darker brownish posterior part of head and disc of elytra, in the latter case, suture, margins, base, and apex of elytra paler. Legs uniformly yellowish. Antennae yellowish or vaguely obscured in middle.

Head rather large, eyes small but convex, tempora long and gradually convex, sparsely but distinctly pubescent. Frontal furrows shallow, evenly impressed, subangulate in median portion, approached in middle, frons therefore rather narrow. 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 impressed.

Pronotum moderately transverse, flattened, with maximum width in apical third. Its sides broadly arcuate in anterior part, nearly straight in posterior part, slightly convex and with shallow or no emargination before hind angles, latter obtuse but pointed apically, often slightly produced outward. Posterior margin straight, oblique or emarginate laterally; anterior margin straight. Anterior angles broadly rounded but distinguishable. Lateral margins rather narrowly reflexed, more widely in their posterior portion. Prebasal transverse impression arcuate, rather deep laterally, without distinct bending in basal foveae which are average in size and depth. Apical transverse impression fine laterally, briefly interrupted medially. Anterior marginal seta placed in about anterior third of pronotum, posterior one—at hind angle. Discal foveae present or absent. Basal surface of pronotum slightly to markedly rugose. Median line faint, deeper near basal margin.

Elytra narrow elongate-ovate, sides subparallel for most of their length, widest near middle. Humeri prominent, though broadly rounded, prehumeral margin markedly oblique, posthumeral sinuation very faint. Elytral apex broadly and commonly rounded, nearly truncate in some specimens, with slight subapical sinuation. Elytral striae gently and irregularly impressed, waved, only three inner striae distinct and continuous, others shallow and shortened, becoming less distinct toward sides. Stria 7 indistinct. Intervals flat and subequal in width: interval 2 only a little wider than interval 3 at level of preapical pore. All elytral striae slightly but distinctly punctured. Stria 2 surpassing level of preapical pore posteriad, striae 3 and 4 joining each other approximately at level of anterior end of apical striole; outer striae usually indistinct, at most, striae 5 and 6 joining each other at level behind median group of umbilicate series. Parascutellar striole and parascutellar pore present. Apical striole long, straight or slightly arcuate, bordered by a distinct carina exteriorly, nearly reaching level of umbilicate pore 7 anteriorly, either interrupted or joining stria (5x 6) anteriorly. Two discal setiferous pores in stria 3, anterior one usually at level between umbilicate pores 3 and 4, posterior one markedly before umbilicate pore 5. Apical triangle markedly elongate, its exterior pore behind mid-length of anterior portion of apical striole. Inner sides of triangles on both elytra feebly convergent anteriad. Preapical pore removed far from elytral apex and located on interval 3 or in sinuation of stria 2, at level or slightly before anterior end of apical striole, at level of umbilicate pore 7. Lateral margins bordered and moderately reflexed.

Microsculpture well-developed over entire body surface, consisting of isodiametric meshes on head, irregular and slightly transverse meshes on disc of pronotum, and distinctly transverse meshes on elytra.

Front tibiae distinctly but shallowly grooved on exterior surface. Two basal segments of male protarsi dilated, markedly transverse, each with massive and obtuse inner tooth.

Aedeagus ( Figs. 15–17 ) rather small, cylindrical, markedly curved at base, with massive basal portion and slender distal portion, ventral side of the latter broadly arcuate, distal part with simple apex in lateral view; in dorsal view, median lobe subparallel-sided for most of its length, with short apical portion of triangular shape, narrowly rounded distally. Sagittal lobe absent. Preputial orifice long, though not reaching basal bulb, gradually narrowing proximally. Parameres long and slender, markedly curved in basal third, nearly straight in apical half, slightly contracted before apex, latter regularly rounded; left paramere clearly longer, with a well-developed ventral apophysis; each paramere bearing 4 apical setae. Endophallus armature consisting of two poorly sclerotized areas: proximal one larger, less heavily chitinized, distal one smaller but more clearly defined, located just before apex, narrowed and attenuated distally in dorsal view.

Sexual dimorphism. Males differ in larger elytra (EW/PW on average, 1.47 vs. 1.44 in females; EW/HW on average, 1.79 vs. 1.73 respectively, in both ratios p≤0.01; EL/PL on average, 2.84 vs. 2.76, p≤0.05), and smaller eyes (YL/L3 on average, 1.12 vs. 1.19 in females, p≤0.01).

Comparative notes. In its small, and subparallel habitus, small eyes and pale color of the upper-side, T. aghiazicus sp. n. is similar to T. semenovi Belousov & Kabak, 1992 and especially T. placidus Jeannel, 1962 from the Tien Shan Mountains in Kazakhstan and Kyrgyzstan ( Jeannel 1962, Belousov & Kabak 1992) as well as to T. bodemeyeri Reitter, 1913 , T. chormaensis Deuve, 1993 , and related taxa from Chinese part of the Tien Shan ( Reitter 1913, Deuve 1993). Nonetheless, the shape of the aedeagal median lobe, which is slender and gradually attenuating toward the apex, is rather specific and only remotely resembles that of T. chormaensis and T. placidus , the species can easily be identified based on two copulatory pieces widely spaced and poorly sclerotized, the distal of which is very short, located just near the apex and pointed apically in dorsal view ( Figs. 15–17 ). A similar structure of the endophallus armature is found only in T. zhdankoi Belousov & Kabak, 1992 from the Terskey Alatau Mountain Range (the Tien Shan mountains in Kazakhstan and Kyrgyzstan) but in the latter species the body is much larger, the median lobe is significantly larger and thicker, and the distal piece of the endophallus armature does not attenuate distally in dorsal view ( Belousov & Kabak 1992).

Distribution. The species inhabits the northern slopes of the western parts of the Narat and Khalyktau mountain ranges, Xinjiang, China.

Bionomics. The species was found only in the alpine zone, at elevations between 3100 and 3800 m, mostly from under stones

Derivatio nominis. The species is named after the Aghiaz River, a tributary of the Tekes River.

Figures

FIGURES 11–12. Trechus Clairville, 1806, habitus, males, paratypes. 11, T. aghiazicus sp. n.; 12, T. cratocephalus sp. n.

FIGURES 13–21. Male genitalia of Trechus spp. n., paratypes: a—lateral view, b—dorsal view. 13—T. saluki sp. n.; 14—T. kashensis Belousov & Kabak, 2001 (from Belousov & Kabak 2001); 15–17—T. aghiazicus sp. n.; 18–21—T. cratocephalus sp. n.