Trechus xiongmao, Belousov & Kabak, 2021

Belousov, I. A. & Kabak, I. I., 2021, Three new species of the genus Trechus Clairville, 1806 from Sichuan (Coleoptera: Carabidae: Trechini), Russian Entomological Journal 30 (4), pp. 401-421 : 402-404

Trechus xiongmao sp.n.

Figs 1–4.

MATERIAL. Holotype ♂, “ China, NW Sichuan, NW of Lixian , 9 km W of Shangmeng, scree above timber-line 3600–3800 m, 23.07.2002, Belousov I. & Kabak I. leg.” [31°40´30´´N / 103° 02´25´´E]. Paratypes: 14(7) ♂♂, 11♀♀, collected with holotype ( BMNH, IZAS, NME, MPU, SMNS, ZSM, CAG, CAK, CBK); 1f ♂, “China, NW Sichuan, NW of Lixian, 10 km WNW of Shangmeng , forest 3350 m, 22.07.2002, Belousov I. & Kabak I. leg.” [31°42´08´´N / 103°02´22´´E] ( CBK) ; 1♀, “China NW Sichuan, NW of Lixian, 10 km WSW of Shangmeng , alp., scree 3850–4000m, 25.07.2002, Belousov I. & Kabak I. leg.” [31°39´40´´N / 103°01´50´´E] ( CBK) .

DESCRIPTION. Small-sized species with body length usually less than 3 mm. Body broad ovate, constricted at pronotal base, very convex. Appendages not long, legs stout ( Fig. 1). Upper side usually dark brownish, suture, margins of elytra, and occasionally disc of pronotum pale reddish; more rarely whole dorsum amber brownish. Head before clypeal suture much paler than behind, boundary not sharp. Legs yellowish. Antennae concolorous, reddish yellow.

Microsculpture well developed over entire surface of both head and pronotum, though becoming shallower on disc of the latter, consisting of isodiametric meshes on disc of head, slightly transverse meshes on anterior portion of pronotum, and markedly transverse meshes on its posterior portion; microsculpture of elytra shallow, consisting of transverse anastomosing lines, surface of elytra with iridescent luster. All upper side micropunctured.

Head of medium size, eyes rather small and flat, tempora long and convex, with a few very short hairs. Frontal furrows regularly impressed, subangulate and approaching one another before middle; frons convex. Supraorbital setae located in lines, distinctly convergent anteriad, posterior seta far behind posterior margin of eye. Pores of both anterior and posterior setae foveolate, though posterior pore less deeply impressed. Mandibles stout, evenly curved. Tooth on right mandible tridentate, its shape rather variable but distal denticle always most prominent. Anterior margin of labrum concave.

Pronotum markedly transverse, convex, with maximum width in apical third, clearly contracted to base, approximately as wide at base as at apex. Its sides broadly arcuate in anterior part, then nearly straight and convergent, with very shallow or no sinuation before hind angles, latter obtuse, blunt, or sharp at apex, always distinct. Posterior margin straight or slightly convex medially, obliquely truncate laterally; anterior margin straight. Anterior angles marked but not salient. Lateral margins bordered and reflexed, lateral groove of average width, clearly expanded posteriorly. Prebasal transverse impression shallow, vaguely delimited, angularly curved in basal foveae, the latter are of average size. Apical transverse impression continuous, well engraved laterally, becoming shallower or even interrupted medially. Discal foveae missing or slightly impressed. Anterior marginal seta placed in about anterior third of pronotum, posterior seta — in hind angle. Basal surface of pronotum distinctly rugose; wrinkles becoming sharper near basal margin. Median line regular, slightly impressed, becoming deeper near prebasal impression.

Elytra broad oval, with arcuate sides, widest just after their middle. Humeri broadly rounded, prehumeral margin evenly arcuate, posthumeral sinuation indistinct. Elytral apex broadly rounded, nearly truncate, with a distinct preapical sinuation. Elytral striae rather deep and regular, nearly entire, even stria 7 visible in its middle portion. Intervals 3–4 rather convex, interval 2 about 1.5 times as wide as interval 1 in their apical third. All elytral striae finely punctured and slightly undulate. Stria 2 surpassing level of preapical pore, occasionally redoubled behind it, often without clear connection with stria 3, latter joining stria 4 at level slightly behind anterior end of apical striole. Striae 5 and 6 joining each other slightly behind median group of umbilicate series or near that level; stria 7 without clear connection with any of other striae. Parascutellar striole and parascutellar seta present. Apical recurrent striole of average length, rather deep and straight, usually not reaching level of mid-distance between umbilicate pores 7 and 8, joining merged stria (5x6) anteriorly. The dominant pattern of striation on apical slope of elytra may be described as follows: ((5x6)xAS)(3x4)(2x3) where each next conjunction ‘x’ is located closer to the elytral apex. Apical triangle (consisting of three pores on the apical slope of each elytron, including the preapical pore) usually slightly elongate, its inner side convergent with suture anteriorly. Preapical pore set at level clearly behind anterior termination of apical striole. Angulo-apical pore usually placed closer to exterior pore than to elytral suture. Lateral margins bordered and markedly reflexed.

Protibiae flattened and grooved on exterior surface; two basal segments of male protarsi dilated, markedly transverse.

Median lobe of aedeagus of average size, subcylindrical, sharply curved at basal third, with straight ventral margin and small apical dilation, apical lamella rather large, its sides gradually narrowed toward apex in lateral view ( Figs 2, 4 ); and nearly parallel sided in dorsal view ( Fig. 3 ). Sagittal aileron of medium size. Parameres of average length, straight in apical half, left one clearly longer, with a well-developed ventral apophysis; each paramere bearing 4 apical setae ( Fig. 2 ). Endophallus armature is similar to that of T. gansuensis Deuve et Quéinnec, 1993 and related taxa, consisting of poorly defined sclerite, S-shaped in dorsal view, and one small scaly area located near left wall of the median lobe.

SEXUAL DIMORPHISM. Males differ in smaller head (PW/HW, on average, 1.32 mm vs. 1.29 mm in females, p≤0.01), larger eyes (YL/TL, on average, 1.34 vs. 1.25 in females, p≤0.05), and less transverse pronotum (PW/PL, on average, 1.41 vs. 1.44 in females, p≤0.05).

COMPARATIVE NOTES. T. xiongmao sp.n. is similar to T. xiei Deuve, 1992 . However, it differs from this species in having larger body size (2.72–3.15, on average, 2.93 vs. 2.44–3.04, on average, 2.81 in T. xiei ), darker color of upper side, broader base of pronotum and longer antennae (see Table 2) and particularly it may be distinguished by the shape of the median lobe, which is much bigger, with endophallus armature more heavily sclerotized, and its distal portion more markedly curved ( Figs 2–4 ).

On the other hand, T. xiongmao sp.n. is similar to T. gansuensis Deuve & Quéinnec, 1993 described from Gansu: “ 120 km au sud-ouest de Lanzhou, Ponggartang” [ Deuve, Quéinnec, 1993] but differs in having more broadly ovate habitus, smaller eyes (their diameter only slightly exceeding length of both tempora and antennomere 3), longer antennae, more transverse pronotum (PW/PL 1.43 vs. 1.36, PW/HW 1.30 vs. 1.26 in T. gansuensis ), wider and more convex elytra (EL/BH 2.24 vs. 2.37) and larger pronotum (EL/PL 2.75 vs. 2.80); the preapical pore removed farther from the apex of elytra, umbilicate pores 1–4 removed from umbilicate pore 5 and placed closer to the base of elytra (the significance of differences in the above morphometric characters was based on the t- criterion, species comparison on the Mann-Whitney criterion is shown in Table 2). Male genitalia of T. xiongmao sp.n. are similar to those of T. gansuensis , but the new species can be readily distinguished by the endophallus armature more developed and by the apex of the median lobe distinctly attenuated downward in lateral view

DISTRIBUTION. The species is known only from the type locality, situated in the upper valley of a small river located west of the village of Shangmeng in the upper basin of the Mengdonggou River , NW of Lixian Town , Li County, Sichuan .

BIONOMICS. The species occurs in a wide belt of altitudes in both the alpine and upper forest zones (though much more common in the latter) at elevations from 3350 to 4000 m. Most specimens were sifted from the forest litter in rather humid habitats.

DERIVATIO NOMINIS. The species epithet refers to the Chinese name of giant panda occurring in the same area.

Figures

Figs 2–7. Male genitalia of Trechus spp. n.: 2–4 — T. xiongmao sp. n., paratype; 5–7 — T. comma sp. n., paratype; 2, 5 — lateral view; 3, 7 — dorsal view; 4 — distal portion, right lateral view; 6 — right paramere, apex. Рис. 2–7. Гениталии самцов новых видов рода Trechus: 2–4 — T. xiongmao sp. n., паратип; 5–7 — T. comma sp. n., паратип; 2, 5 — сбоку; 3, 7 — сверху; 4 — дистальнаЯ часть, справа; 6 — верШина правой парамеры.