Trechus maoniu, 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 : 462-465

Trechus maoniu sp. n.

( Figs 12, 13–14 )

urn:lsid:zoobank.org:act:35CF4C2F-6F7A-4435-AE4F-484E208FEDA4

Type material: Holotype: 1(1) ♂, “ China, Sichuan, WNW of Danba, ~ 10. 5 km S of Bianer (= Bianr ), 30º57´40´´N / 101º32´38´´ E— 30º57´36´´N / 101º32´45´´ E, 4640–4855 m, 23.08.2004, Belousov I. & Kabak I. leg.” ( ZISP) . Paratypes: 31(10) ♂♂, 18♀♀, collected with holotype ( IZAS, MPU, BMNH, ZISP, ZSM, CAG, CBK, CDW, CJS, CVZ); 16(7) ♂♂, 16(2) ♀♀, “ China, Sichuan, WNW of Danba, ~ 10 km S of Bianer (= Bianr ), 30º57´55´´N / 101º33´02´´ E— 30º57´48´´N / 101º33´07´´ E, H~ 4490–4660 m, 22.08.2004, Belousov I. & Kabak I. leg.”( IZAS, ZISP, ZSM, CBK, CAK) .

Description. Species of average size, body elongate-oval, markedly constricted at pronotal base, subconvex ( Fig. 12). Appendages of medium length. Upperside relatively pale, yellowish brown, with darker head and disc of elytra. Anterior part of head, pronotum, suture and margins of elytra reddish. Legs uniformly yellowish. Antennae yellowish, slightly obscured from antennomeres 4–5.

Head rather large, especially compared to pronotum, eyes small and slightly salient, tempora long and moderately convex, without distinct pubescence. Frontal furrows evenly impressed, subangulate and approaching in the middle. Supraorbital setae located in lines parallel to body axis, posterior seta located far behind posterior margin of eye. Pores of both anterior and posterior supraorbital setae foveolate, though posterior one less deeply impressed. Tooth on right mandible tridentate, with rather long basal margin, distal denticle being more isolated than the two others.

Pronotum subcordate, transverse, with maximum width at apical third, markedly constricted at base. Discal foveae small and shallow. Pronotal sides broadly arcuate anteriorly, straight or slightly sinuate posteriorly; hind angles rather large, mostly rectangular, pointed at apices. Posterior margin barely convex medially, oblique laterally; anterior margin slightly concave. Anterior angles not salient. Lateral margins narrowly reflexed, lateral groove rather narrow, clearly expanded posteriorly. Prebasal transverse impression not deep, curved in basal foveae, the latter large and deep. Apical transverse impression shallow, more distinct laterally. Anterior marginal seta slightly shifted anteriad compared to other related species (on average, level to 25% pronotal length), posterior seta located at hind angle. Base of pronotum coarsely rugose. Median line slightly impressed, becoming deeper near basal margin.

Elytra broad, oval, rather flat, widest near their mid-legth or slightly behind, approximately as wide at humeral area as at level of preapical sinuation, with widely arcuate sides. Humeri broadly rounded, prehumeral margin evenly arcuate, posthumeral sinuation barely distinguishable. Elytral apex narrowly rounded, with a slight subapical sinuation. Elytral striation not deep, but rather even and regular, even stria 7 partially visible. Outer striae beginning with stria 5 much shallower and more distinctly waved. Inner interspaces subconvex, outer ones flat. Interspace 1 only slightly narrower than insterspace 2 in posterior half and nearly as wide as insterspace 2 in anterior half. All elytral striae finely punctured. Striation on apical declivity as follows: stria 3 joining stria 4 very close to elytral apex, connection of striae 2 and 3 usually slightly farther from elytral apex, stria 5 usually joining stria 6 at level of umbilicate pores 6, outer striae beginning with stria 5 either interrupted posteriorly or joining apical striole. Parascutellar striole very short, not joining any striae posteriorly. Apical striole deep, average to long, nearly straight or slightly curved inward anteriad, apical carina rather salient. Pores on apical slope arranged in a triangle moderately to markedly elongate, its inner side slightly divergent with suture posteriad. Preapical setiferous pore markedly shifted anteriad, located before anterior termination of apical striole. Apical cross of striae 2 and 3 distinct. Lateral groove of average width, slightly expanded at humeral area.

Microsculpture well developed over entire body surface, though becoming much shallower on disc of both pronotum and elytra, consisting of isodiametric meshes on head, irregular and slightly transverse meshes on disc of pronotum, and markedly transverse meshes on elytra.

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

Aedeagus medium-sized, angularly bent near base; with maximum width after its mid-length in lateral view and before mid-length in dorsal view; ventral margin nearly straight for most of its length; apical part attenuated and directed slightly downwards, with a small button-like apex ( Figs 13–14 ). In dorsal view, median lobe gently S-shaped, gradually attenuated in its apical third; apex widely rounded. Sagittal lobe well developed. Basal orifice markedly emarginate. Parameres slender, nearly straight in apical half, truncate or widely rounded apically; left one clearly longer, with a well-developed ventral apophysis; each paramere bearing 4 apical setae. Endophallus armature typical for the kozlovi -group, consisting of two rather well-sclerotized pieces, of which proximal one is considerably larger, situated near left wall of median lobe; distal one small, subtriangular in lateral view, comma-shaped in dorsal view.

Sexual dimorphism. Males differ in having longer elytra: EL/EW, on average, 1.35 vs. 1.32 in females (p≤0.01); EL/PL, on average, 3.05 vs. 3.00 in females (p≤0.05).

Comparative notes. Doubtless, this species is most closely related to T. suopoensis sp. n. from the mountains located east of Danba City. Trechus maoniu sp. n. clearly differs from the above species in the following external characters (for morphometric characters, the significance level based on t- criterion is p≤0.001): size larger (average body length 3.35 mm vs. 3.07 mm in T. suopoensis sp. n.), body more flattened (EL/BH, on average, 2.71 vs. 2.56 in T. suopoensis sp. n.), color of upperside paler (yellowish brown vs. blackish brown), head larger (PW/HW, on average, 1.19 vs. 1.23 in T. suopoensis sp. n.), neck wider (compared to anterior margin of pronotum); eyes smaller (YL/TL, on average, 1.38 vs. 1.74 in T. suopoensis sp. n., YL/L3, on average, 1.11 vs. 1.24 in T. suopoensis sp. n.), elytra wider (EW/PW, on average, 1.71 vs. 1.60 in T. suopoensis sp. n., EW/HW, on average, 2.05 vs. 1.98 in T. suopoensis sp. n.), lateral groove of both pronotum and elytra (especially in humeral area) narrower and margins less distinctly reflexed, legs longer (EL/TiL on average, 2.29 vs. 2.38 in T. suopoensis sp. n.) (for more differences based on the Mann–Whitney criterion see Table 2). The median lobe of the aedeagus is wider in the apical third, clearly S-shaped in dorsal view; the distal piece of the endophallus armature is considerably smaller, comma-like in dorsal view (larger and oblong in T. suopoensis sp. n.) ( Figs 13–14 vs. Figs 2–4 ). The new species is clearly distinguished from T. bianericus sp. n. inhabiting the same mountains at lower elevations by the following characters: larger size, paler color of the upperside (although antennae, by contrast, obscured from antennomeres 4–5); larger and more conical eyes and less convex tempora; narrower pronotum with more developed sinuation before hind angles, which are more produced; elytra wider and more flattened, with more rounded humeri, and by more slender appendages (for further differences see Table 2). Additionally, T. maoniu sp. n. clearly differs from T. bianericus sp. n. in the male genitalia: median lobe slenderer, distinctly S-shaped and clearly narrowing distally in dorsal view; endophallus armature more heavily sclerotized, with smaller distal sclerite, etc. ( Figs 13–14 vs. Figs 9–11 ).

Distribution. T. maoniu 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 alpine zone, where it had been collected from under stones at elevations from 4490 to 4855 m.

Derivatio nominis. The species epithet is derived from the Chinese name of Yak.

Figures

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.

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