Himalotrechus humeratus, Belousov & Kabak & Schmidt, 2019

Belousov, Igor A., Kabak, Ilya I. & Schmidt, Joachim, 2019, A new genus of Trechini beetles from the Eastern Himalaya (Coleoptera: Carabidae), Zootaxa 4544 (4), pp. 581-588 : 585-588

Himalotrechus humeratus sp. n.

( Figs 1, 2–3 , 4 )

Type material: Holotype: INDIA: 1 male, with label data “ India , Arunachal Pradesh, N of Bomdila, NW Chander, 10–15 km NW of, 27°25´N 92°22´E, ca 3200 m, 18 VI.2008 / Reuter” (coll. J. Schmidt). Paratypes: 2 females, collected together with holotype (coll. I. Belousov & I. Kabak, coll. J. Schmidt) .

Description. Large-sized species, with elytra extraordinarily convex and shortly ovate ( Fig. 1), body length 4.6–5.1 mm. Legs and antennae of medium length, median antennomeres markedly longer than wide.

Color: amber-brownish, rather dark; legs and antennae uniform brownish-yellow.

Microsculpture: well distinguished throughout the dorsal surface, though rather shallow, consisting of markedly transverse meshes on head (even on vertex), and of transverse, partially anastomosing lines on pronotum and elytra. Ventral surface completely covered with more distinct, less transverse meshes, becoming coarser on the anal sternite and on anterior parts of the other abdominal sternites.

Head: trapezoid, rather narrow compared to pronotum, PW/HW 1.60–1.65. Frons convex, relatively narrow; frontal furrows continuous and rather deep, even posteriorly, angularly curved in the median part. Parietal transverse impression deep. Eyes small (EyL/TL 0.83–0.88, L3/EyL 1.07–1.23), slightly convex, non-protruding, clearly shorter than tempora, which are glabrous, long, rather convex. Supraorbital pores located on axis parallel to the mid-line of body. Anterior supraorbital pore foveolate, the posterior one with an oblique impression directed to the eye. Labrum sexsetose, transverse, its anterior margin with a weak emargination becoming more distinct between inner setae. Mandibles slender, nearly straight, slightly curved in distal third. Premolar and distal denticle of the retinaculum on the right mandible far removed from each other, with a deep and long emargination between them ( Fig. 2 ); median denticle more or less reduced, distinguishable mostly as a small tubercle just near premolar. Mentum tooth faintly salient, rounded or truncate, without distinct emargination; ventral surface of labial tooth with a small oval impression. Six submental setae equidistantly located across submentum. Mentum and submentum fused, without distinct suture between them. Maxillary palpi elongate, glabrous, segments 2 and 3 without distinct hairs ( Fig. 3 ). Penultimate segment of the labial palpi bisetose. Glossa markedly salient medially, with two median setae which are much longer than the lateral ones. Paraglossae moderately long, slender, slightly curved and distinctly pubescent. Antennae of medium length, EL/AL 1.18–1.25; middle antennomeres nearly twice as long as wide, L3/ W3 2.67 –2.72; L3/L2 1.36–1.52.

Pronotum: large, moderately transverse (PW/PL 1.22–1.26), much stronger constricted anteriad than posteriad (PW/PB 1.22–1.28), with basal margin significantly longer than anterior margin (PB/PA 1.27–1.42); sides broadly rounded in middle and towards the front angles, nearly straight posteriorly, very shortly sinuate just before the hind angles. The latter subrectangular to obtusangular, with small apices produced outward. Anterior margin salient, with anterior angles slightly shifted posteriad. Basal margin straight or slightly salient in median part, sinuate laterally. Lateral margins narrowly reflexed in anterior part, moderately in median part and very markedly in posterior part. Prebasal transverse impression shallow, rather short (about half the basal margin of pronotum), visible only laterally, distinctly curved in the basal foveae. Apical transverse impression subtriangular in shape, shallow but distinct and continuous. Basal surface smooth, with one more oblong fovea on each side in addition to the prebasal impression and, occasionally, with a few wrinkles in the median portion. Basal foveae relatively small but deep. Median line rather deep, in particular on disc and near pronotal base. Discal foveae shallow, occasionally consisting of a few irregularly shaped impressions. Two lateral setiferous pores on each side of pronotum, the anterior one slightly behind anterior third of pronotum (35–39%, on average, 37%).

Elytra: very convex (EL/BH 2.04–2.06), wide (EL/PL 2.30–2.38; EW/PW 1.44–1.51; EW/HW 2.34–2.42), broadly ovate (EL/EW 1.25–1.31), with maximum width in anterior third; sides entirely convex, without posthumeral sinuation. Prehumeral margin almost perpendicular to the elytral suture, with a distinct tuberculum near the mesothoracic constriction. Humeri prominent though rounded. Posterior portion of elytra markedly narrowed towards apex. Lateral groove rather wide; margins slightly reflexed, more markedly in the humeral area; lateral border distinctly hooked and disappeared anteriorly at level of anterior end of stria 5. All elytral striae well- impressed and very coarsely punctate, though becoming very shallow near base, even striae 7 and 8 distinct for most of their length, located close to the marginal groove. Striolation on apical slope as follows: stria 2 nearly reaching the angulo-apical pore, other striae either free or irregularly joining each other. Interspaces convex. Parascutellar pore present, parascutellar striole developed, but rather short. Apical striole medium in length, slightly curved or sinuate, directed to stria 5 but without distinct connection with the latter. Two discal pores in anterior half of elytra, both attached to stria 3; preapical pore lacking; discal formula 17–19, 43–45. Apical slope with exterior pore deeply impressed, nearly foveolate, contrasting in this respect with small angulo-apical pore. Umbilicate series well-aggregated, only pore 5 slightly shifted from lateral margin and pores 7 and 8 more spaced, all pores of the humeral group equidistant; umbilicate formula: 8–9, 12–14, 16–19, 21–24, 59–60, 64–65, 80–81, 87–89.

Ventral surface: metepisternites smooth, approximately 1.5 times as long as wide. One paramedian seta on each side of abdominal sternites. Anal sternite with two setae in male and four setae in female.

Legs: fore tibia thin, markedly grooved on exterior surface, glabrous on anterior surface. Male protarsi with two basal segments dilated, their adhesive appendages short and ovate. In pro- and mesotarsi, ventral hyaline appendages of segment 4 rather narrow, parallel-sided, attenuated distally, distinctly not reaching the apex of tarsomere 5. Hind tibia: EL/HTi 2.18–2.24; HTi/HTa 1.45–1.52.

Aedeagus ( Fig. 4 ): evenly curved in lateral view, its apex gently attenuated ventrally. In dorsal view, median lobe rather thick, its lamella short, distinctly curved. Sagittal aileron not large but distinct. Basal orifice moderately concave. Endophallus armature poorly sclerotized, consists of asymmetrical scaly areas confined to the apical half of the median lobe. Parameres robust, each bearing 5–6 apical setae, the left paramere longer and provided with a well developed ventral apophysis.

Distribution. Eastern Himalaya; probably endemic to a mountain range N of Bomdila in the Indian State of Arunachal Pradesh.

Bionomics. The species was found in the cloud forest zone at an elevation of approximately 3200 m a.s.l.

Etymology. The species’ epithet refers to the conspicuous, prominent humeri giving the new species a distinctive appearance.

Figures

FIGURE 4. Male genitalia of Himalotrechus humeratus gen. n., sp. n.: a—lateral view; b—dorsal view; c—parameres.

FIGURES 2–3. Himalotrechus humeratus gen. n., sp. n., paratype, mouth parts: 2—right mandible; 3—right maxillary palpus.