Sinotrechiama yunnanus, Belousov & Kabak & Liang, 2019

Belousov, Igor A., Kabak, Ilya I. & Liang, Hongbin, 2019, New species of the tribe Trechini from China (Coleoptera: Carabidae), Zootaxa 4656 (1), pp. 143-152 : 147-148

Sinotrechiama yunnanus sp. n.

( Fig. 5 )

Type material: Holotype: CHINA: 1♀, with label data “ China, Yunnan, Dayao, Santai Town , pass to Xiaobaicaol- ing, 3105 m, N 26.05615, E 101.05448 ”; “ 2012.V.29, day, under stone, mixed forest, Shi Hongliang leg., Institute of Zoology , CAS. [In Chinese]: Dayao Xian, Santai Xiang, Xiaobaicaoling Yakou” ( IOZ).

Description. Medium-sized species, body length 5.8 mm, appendages slender ( Fig. 5 ).

Upper-side mostly pitchy black, with slightly paler amber reddish anterior portion of head (before clypeal suture, except for a small median blackish spot along the anterior margin of labrum), vertex, basal portion of pronotum, base, margins and suture of elytra. Appendages yellow reddish, antennae with middle segments vaguely obscured (beginning from segment 4), legs with femora slightly darkened.

Microsculpture very fine, consisting of well-engraved rather small isodiametric meshes on head, slightly impressed irregular transverse meshes on pronotum and fine transverse lines on elytra. Entire dorsum finely micropunctured. Elytra and pronotum clearly iridescent.

Head ovate, medium-sized ( PW / HW 1.35). Eyes average for the genus (YL/TL 1.34), regularly protruding, tempora rather convex. Frontal furrows complete, widely arcuate, subparallel in middle portion, deepest near clypeal suture and at level near posterior margin of eyes. Parietal transverse impression rather deep. Neck relatively narrow. Antennae slightly longer than elytra (AL/ EL 1.08). Antennomere 3 considerably longer than eye diameter (L3/YL 1.30), its ratios: L3/L2 1.70, L3/ W3 3.33. Labrum markedly transverse, with anterior margin slightly concave for most of its length and barely salient medially. Tooth of right mandible tridentate, with distal denticle longest, median and proximal denticles much shorter and markedly approaching each other. Segments of maxillary palpi long and fusiform, glabrous; penultimate segment of labial palpi quadrisetose. Labial suture distinct, though very fine, slightly sinuate. Labial tooth not large, bidentate. Apart from six typical submental setae, still one much smaller seta is present between median pair of setae. Ligula obtusangular, blunt at apex, bearing two apical longest setae medially and three shorter lateral setae on each side. Paraglossae arcuate, clearly pubescent along their inner margin.

Pronotum transverse, ( PW / PL 1.34, PW /PB 1.71), clearly wider at apex than at base (PA/ PB 1.10). Lateral margins broadly rounded for most of their length, with short emargination before hind angles. Anterior margin straight, posterior margin barely concave medially, distinctly emarginate laterally. Hind angles rectangular, with apices slightly pointed posteriad. Front angles rounded, not clearly produced anteriad. Pronotal disc subconvex, with shallow discal foveae. Basal foveae large and deep. Prebasal impression deep, subparallel to basal margin, apical impression shallow. Lateral groove rather wide, clearly narrowed anteriorly and slightly widened posteriorly, fused with basal fovea. Base of pronotum smooth, with a few slight wrinkles. Median line well-impressed, though not reaching the anterior and posterior margins. Two lateral setae, the anterior one located in anterior third of pronotum (PSa approximately 32%), and the posterior one—just before hind angle. Three-four small setae on each side of pronotal disc.

Elytra ovate, rather narrow ( EL / EW 1.54), broadest near mid-length, depressed along suture but steeply sloped basally, laterally and apically, their ratios: EL/ PL 3.17; EW/ PW 1.54; EW/HW 2.08, EL/BH 2.62. Lateral margins slightly rounded, nearly subparallel in median portion, humeri oblique and rounded though marked; preapical sinuation distinct, elytral apices slightly truncate. Lateral groove not wide, gradually narrowing anteriad. Basal border of elytra very short. Elytral striae markedly differentiated: two inner striae deep and distinctly punctured (stria 1 being rather sharp), stria 3 nearly complete, striae 4 distinct only on elytral disc, stria 5 only partially traceable while striae 6 and 7 completely effaced. Apical recurrent striole well-impressed, carinate, markedly curved and directed to stria 3 anteriorly (at least so on left elytron). Parascutellar striole deep, parascutellar pore present. Inner intervals subconvex, others flat. Eight pores on each elytron, including: two pores in anterior half of stria 5, one anterior pore located more or less clearly in anastomosis of striae 2 and 3, one preapical pore in the apical cross of striae 2 and 3 at level clearly behind anterior termination of apical striole ( DP 86.8%), and the remainder four pores are rather equally distributed in stria 3. Preapical pore and two apical pores form an elongate apical triangle, angulo-apical pore approximately in middle between elytral suture and exterior pore. All umbilicate pores well-aggregated within their groups, equidistant, except for pores 7 and 8 which are markedly more spaced. Umbilicate formula U1–8: 9.2%, 13.2%, 17.1%, 21.1%, 64.9%, 69.1%, 82.2%, 89.3%.

Metepisternites clearly longer than wide. Abdominal sternites with 4–10 setae (including a pair of paramedian ones) approximately along their posterior edge. Anal sternite quadrisetose in one female specimen known.

Legs long, fore tibiae deeply grooved exteriorly, nearly carinate, glabrous on anterior surface. Hind tibia ratios: EL/HTi 1.82, HTi/HTa 1.37.

Comparative notes. The new species differs readily from other congeners in having the pronotum markedly transverse ( PW / PL 1.34) (at most, slightly transverse in other species: PW / PL 1.07–1.28, see Belousov & Kabak 2003, Deuve 2004, Uéno, 2006), with lateral groove of medium width (very narrow or even reduced posteriorly in most other species) and combination of exterior elytral striae reduced with only two setiferous pores in stria 5.As far as the shape of the pronotum with distinct and rather wide lateral groove is concerned, this species is most similar to the two closely related species: S. duboisi Deuve, 2004 and S. parvus Uéno, 2006 . However, the new species differs readily from these two species, apart from the above listed characters, in the longer and deeper emargination of the pronotal sides before hind angles and less convex tempora.

Despite the deviated shape of the pronotum, the new species shares all major characters of the genus Sinotrechiama Uéno, 2000 , including the presence of setae on the disc of the pronotum and the anterior discal setiferous pore of the elytra located in the position typical for other congeners, at least so on the left elytron (it is worth noting that the striae are suppressed on the basal slope hampering assessment of this character; additionally, one specimen available is not sufficient for evaluation of this unstable character which is reliable only for larger samples).

Based on all available characters, Sinotrechiama yunnanus sp. n. seems to be closer to the species related to S. tronqueti Deuve, 1995 than to S. duboisi and the allied S. parvus , though geographically it is far away from both these species groups. The duboisi species group appears to be rather isolated within the genus Sinotrechiama based on the heavily sclerotized endophallus armature typical for its members ( Deuve 2004).

Distribution. Sinotrechiama yunnanus sp. n. is the first member of the genus found outside of Sichuan Province. Therefore, the known area of distribution of the genus is significantly extended southwestward. S. yunnanus sp. n. was collected in the Xiaobaicaoling Pass, Santai Town, Dayao County, Yunnan.

Bionomics. Sinotrechiama yunnanus sp. n. has been found in a mixed forest at an elevation of approximately 3100 m a.s.l.

Derivatio nominis. The species is named after the province where it has been found.

Figures

FIGURE 5. Sinotrechiama yunnanus sp. n., female holotype, habitus.