Trechus sharovae, 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 : 407-412

Trechus sharovae sp. n.

Figs 9–13.

MATERIAL. Holotype ♂, “ China, NW Sichuan, NE of Lixian, N of Tonghua,basin of river near Pingshitou,H~ 3300–3500 m, 19.08.2002, Belousov I.&Kabak I.leg.”[31°43´49´´N / 103°23´11´´E — 31°44´15´´N / 103°22´54´´N]. Paratypes: 13(4) ♂♂, 5♀♀, collected with holotype ( IZAS, NME, MPU, ZSM, CAG, CAK, CBK, CJS); 3(3) ♂♂, “ CH, NW Sichuan, NE of Lixian , N Tonghua, basin of river near Pingshitou , S of Shibanpengzi , H~ 3600–3900 m, 20.08.2002, Belousov I. & Kabak I. leg.” [31°44´30´´N / 103°22´50´´E — 31°44´41´´N / 103°22´50´´E] ( CBK); 1(1) ♂, “ CH, NW Sichuan, NE of Lixian , N Tonghua, basin of river near Pingshitou , S of Shibanpengzi , H~ 3900 m, 22.08.2002, Belousov I. & Kabak I. leg.” [31°44´41´´N / 103°22´49´´E, corrected height = 3600 m] ( CBK) .

DESCRIPTION. Medium-sized species, body length usually slightly less than 4 mm, habitus robust and subparallel sided, dorsum moderately convex ( Fig. 9). Legs and antennae rather slender; middle antennomeres much longer than wide. Color of upper side rather concolorous, reddish brown, usually with darker hind part of head and disk of elytra; the suture and margins of the latter normally slightly paler, amber reddish. Legs pale amber reddish, antennae vaguely obscured from segments 3–4.

Microsculpture well distinguished, consisting of isodiametric meshes on head, very transverse meshes on pronotum, and transverse lines on elytra. Pronotum with slight, elytra with distinct iridescence. Micropunctures well developed on the whole upper surface.

Head of medium size. Frontal furrows well impressed, angularly curved in their anterior third. Parietal impression indistinct. Supraorbital setiferous pores located in lines subparallel to body axis; posterior pore more deeply foveolate, located at level clearly behind posterior edge of eye. Eyes medium-sized, evenly convex; tempora rather long, slightly convex, glabrous. Mandibles stout, evenly curved on their exterior margin. Tooth on right mandible tridentate, its shape rather variable but distal denticle always most prominent and more isolated from other denticles. Labrum with anterior margin concave.

Pronotum moderately transverse, subconvex on disk, with maximum width clearly before its mid-length, marginally wid- er at base than at apex. Sides slightly to moderately sinuate before hind angles.Latter medium-sized, subrectangular, point- ed apically. Basal margin nearly straight, barely emarginate on sides. Anterior margin rectilinear to slightly concave; front angles rounded and barely salient. Prebasal transverse impression moderately impressed, located far from and subparallel to basal margin, sharply curved in basal foveae. The latter large and deep, often with a triangular impression in bottom. Basal surface longitudinally rugose. Preapical transverse impression vague and shallow, more distinct laterally, often with a few coarse punctures or impressions medially. Lateral groove rath- er wide, narrowed to front angles and dilated to pronotal base. Median line distinct, more deeply impressed toward base, shortened anteriorly, reaching basal margin of pronotum. Discal foveae shallow or indistinct.

Elytra ovate, subconvex, with maximum width near their mid-length, relatively narrow (as compared to other members of the group), elytra commonly rounded at apex. Humeri rounded. Preapical sinuation distinct. Two discal setiferous pores in stria 3. Preapical pore located in the apical cross, much closer to stria 2 than to stria 3, at level markedly behind anterior termination of apical striole. Apical triangle slightly elongate, its inner side normally slightly divergent posteriad or parallel to elytral suture. Angulo-apical pore approximately in middle between exterior pore and elytral suture. Umbilicate pores well aggregated, umbilicate pores 7 and 8 most spaced (compared to those within other groups). Elytral striae 1–5 well impressed and distinct for most of their length, though becoming increasingly shallower toward sides; all striae coarsely punctured. Stria 6 very shallow, even in its median part, stria 7 only partially discernible. Inner interspaces slightly convex, others flat. Striation on apical slope rather shallow: striae 3 and 4 joining each other at level between anterior termination of apical striole and preapical pore, striae 5 and 6 either independently directed to apical striole or disappearing posteriorly without clear connection. Striation on apical slope, although rather shallow, especially striae 5 and 6, could be summarized as follows: (5xAS|5x6xAS)(3x4)(2x3). Parascutellar pore present, parascutellar striole well developed, rather long. Apical striole sharply engraved; rather straight, directed to the site of stria 5 anteriorly and abruptly interrupted there. Lateral groove narrower than average for the group, but wider than in most other groups of the genus, margins slightly and evenly reflexed throughout. Lateral border with a distinct hook anteriorly.

Protibiae thick, especially in apical half, barely grooved on exterior face in distal third, their anterior surface glabrous except for its innermost apex bearing a few rudimentary hairs. Metatibiae slender, nearly straight, moderately thickened distally. Male protarsi with two basal segments markedly dilated and inwardly dentate; both segments 1 and 2 transverse.

Aedeagus relatively large (compared to body size) and thick, markedly curved at basal portion, rather bulky in middle portion ( Figs 10–13 ). Apical portion attenuating downward, ending with a well-developed and oblique button, adjacent portion of ventral margin markedly sinuate. Sagittal aileron missing; basal orifice slightly concave. Endophallus armature consisting of two large and heavily sclerotized sclerites typical for members of the group but their shape and position deviate compared to other species: distal margin of longer sclerite semicircular, its proximal portion markedly concave. Parameres of medium length, each bearing 4–5 apical setae; left paramere longer, with a ventral apophysis.

SEXUAL DIMORPHISM. Males differ in larger body size (on average, 3.12 mm vs. 2.99 mm in females, p≤0.01) and proportionally longer elytra (EL/EW, on average, 1.35 vs. 1.33 in females, p≤0.05) and longer antennae (EL/AL, on average, 1.18 vs. 1.20 in females, p≤0.05).

COMPARATIVE NOTES. Externally, the species is similar to other members of the group, especially to smaller

Table 1. Morphometric characters of Trechus species. Abbeviations are as indicated in Material and Methods.

Таблица 1. Морфометрические приЗнаки видов рода Trechus . СокраЩениЯ укаЗаны в раЗделе «Материал и методы». species like T. trachypachys Sciaky et Pavesi, 1995 , T. altitudinum Deuve, 2004 , and T. kurbatovi Belousov et Kabak, 2000 . From the former species which is known only from female specimens, it differs mostly in paler coloration and shape of pronotum with basal margin less oblique at sides and lateral margins less sinuate before hind angles. On the other hand, the membership of T. trachypachys in the validicollis species group, as it was noted earlier, needs to be confirmed, see also [ Belousov, Kabak, 2000]. Among species with known males, T. altitudinum seems to be most similar to T. sharovae sp.n. Their closeness is also consistent with their neighboring distribution (approximately 100 km between the type localities). Both species share roughly the same coloration, habitus and very similar structure of the male genitalia: median lobe rather short and stout, with short apex and large endophallus armature filling up nearly all the lumen of the median lobe. However, T. sharovae sp.n. differs in having the median lobe with slenderer apical portion, deeper sinuation of ventral margin before apex and more developed button-like apex; endophallus armature readily differs in the main copulatory piece with distal portion much narrowly rounded vs. broad and subangular in T. altitudinum . T. sharovae sp.n. is also similar to T. kurbatovi . Externally, it differs from the latter species mainly in the structure of pronotum with hind angles which are smaller and less acute. The structure of the male genitalia is significantly different: median lobe more robust, ventral margin of apical portion much deeper emarginate, and the main copulatory piece more developed and complexly twisted, less elongate, with apical portion much more broadly arcuate (vs. falcate in kurbatovi ) and apical lamella more acute (broadly rounded in kurbatovi ) in dorsal view.

DISTRIBUTION. The species is known only from the upper valley of the Sanchagou River located north of the township of Tonghua, Li County, Sichuan.

BIONOMICS. The species was found in the forest zone at elevations from 3300 to 3900 m.

Table 2. Statistically significant differences between Trechus species (Mann-Whitney criterion, both sexes). Abbeviations are as indicated in Material and Methods. Таблица 2. Статистически Значимые раЗличиЯ между видами рода Trechus (U-критерий Манна- Уитни, оба пола). СокраЩениЯ укаЗаны в раЗделе «Материал и методы» DERIVATIO NOMINIS. We are honored to name this species in the memory of the late professor Inessa Khristianovna Sharova for her invaluable contribution to our knowledge of carabid beetles.

Acknowledgments. We are very grateful to Drs. S.-I. Uéno (Tokyo), Yu. Imura (Yokohama), A. Konstantinov (Washington), B. Březina (Prague) and A. Gitzen (Neuhofen) for their help in our research projects on Chinese Trechini during different periods of time. We also thank Dr. A.E. Korolev (Saint-Petersburg) for his help in mounting specimens of the new Trechus species collected in China.

Competing interests. The authors declare no competing interests.

Figures

Figs 10–13. Male genitalia of Trechus sharovae sp. n., paratypes: 10, 12 — lateral view; 11, 13 — dorsal view. Рис. 10–13. Гениталии самцов Trechus sharovae sp. n., паратипы: 10, 12 — сбоку; 11, 13 — сверху.