Puertrechus Belousov & Kabak

Belousov, Igor A. & Kabak, Ilya I., 2014, A new genus of trechine beetles, Puertrechus gen. n., with two new species and a new species of Dactylotrechus Belousov et Kabak, 2003 from Southern China (Coleoptera: Carabidae: Trechinae), Zootaxa 3856 (3), pp. 375-398 : 382-386

Genus Puertrechus Belousov & Kabak , gen. n.

Type species: Puertrechus mengsaensis Belousov & Kabak , sp. n.

Diagnosis. The genus is characterized by the combination of the following characters: pronotum with digitiform hind angles, complete lateral border and one anterior lateral seta; elytra with three (including preapical) discal setiferous pores in stria 3 and one (very seldom two) discal setiferous pore on site of stria 5; median lobe of the aedeagus impressed on the ventral surface; its distal part dilated in a spoon-like structure; endophallus armature spatulate.

Description. Medium-sized apterous trechines with shortly ovate convex body and strong constriction at base of pronotum. Antennae and legs medium in length and rather thin, tibiae nearly straight. Colour of body rather dark. Body surface, including underside, glabrous.

Head large, though markedly narrower than pronotum. Eyes well developed and rather convex, tempora completely glabrous and weakly convex. Frontal furrows entire, well impressed in median and anterior parts, shallow posteriorly. Two supraorbital setiferous pores on each side of head, the anterior being strongly, and posterior one slightly foveolate. Two long clypeal setae on each side of head. Labrum sexsetose, very seldom with seven setae. Mandibles rather robust, weakly and gradually curved; premolar on the right mandible missing, i.e. the proximal denticle is not isolated from the remainder of the tooth. Both maxillary and labial palpi rather stout, with ultimate segments subcylindrical, slightly attenuated toward apex. Maxillary palpi glabrous, only segment 2 with more or less distinct seta on its inner-anterior margin; penultimate segment of maxillary palpi strongly dilated distally and markedly shorter than ultimate. Penultimate segment of labial palpi quadrisetose, only marginally shorter than the last one. Glossum triangular-shaped, blunt at apex, with two longer median setae and a few shorter lateral setae. Paraglossae rather short though strongly protruding beyond anterior termination of ligula, without distinct hairs. Labial tooth rather long, wide, distinctly bidentate or broadly rounded at apex, directed forward and upward, with or without longitudinal groove on ventral surface; epilobes at base with distinct transverse border markedly dilated in median portion. Four very long submental setae corresponding to sublateral and median setae; subangular setae extremely thin and short, nearly reduced, often missing (? broken); occasionally one more short median seta. Submentum and mentum fused together, with arched callosum-like structure, labial suture very fine, easily distinguishable only in median portion. Central setae of both stipes and cardo very long, much longer than adjacent setae.

Pronotum cordiform, with sides strongly constricted and sinuate before hind angles. Latter modified into digitiform processes similar to those of Queinnectrechus Deuve, 1992 ; basal margin deeply emarginate near hind angles, weakly convex elsewhere. Both anterior and posterior lateral setae present. Lateral border of pronotum entire though becoming extremely fine in posterior half. Lateral groove of pronotum narrow in anterior part, degenerated posteriorly. Basal foveae small and deeply impressed. Prebasal transverse impression distinct. Apical transverse impression shallow. Median line distinct.

Elytra briefly ovate and evenly convex, humeri oblique. Base of elytra with an impression matching the shape of pronotal base. Lateral groove very wide, much wider than that of the pronotum. Lateral margins smooth and glabrous, not ciliated. Elytral striolation strongly reduced, inner striae visible only as fragments. Parascutellar striole distinct, deeply impressed, parascutellar pore present. Apical striole short and weakly impressed. Elytral chaetotaxy very characteristic: apart from two normal discal setiferous pores in stria 3, one more setiferous pore on site of stria 5 located in basal third of elytra. Preapical pore markedly shifted anteriad and located in cross of striae 2 and 3, clearly before anterior termination of apical striole. Both angulo-apical and exterior pores present. Humeral group of umbilicate series not aggregated: the first umbilicate pore more or less strongly shifted inward; all other umbilicate pores located approximately the same distance from lateral margin. Umbilicate pores 7 and 8 more spaced than others within their groups.

Microsculpture effaced to shallow depending on the species. All surface evenly and strongly micropunctured. These micropunctures distributed in more than two longitudinal rows on each interspace of elytra.

Ventral side covered with rather even and fine microsculpture consisting of strongly transverse meshes in median part of the second and third visible abdominal sternites, and of transverse serrate lines elsewhere. Metepisternite much longer than wide, smooth, only with a few very sparse and shallow punctures. Suture between second and third visible abdominal sternites effaced medially. Only one pair of paramedian setae on abdominal sternites 3-5; anal sternite with two setae in male and four setae in female.

Front tibiae distinctly grooved on exterior surface and shortly and rather sparsely pubescent in apical fifth on anterior surface. Two basal segments of male protarsi dilated and dentate, bearing on their underside very small adhesive appendages.

Aedeagus ( Figs. 8–9 and 13–14 ) small, its median lobe slender, moderately curved, distinctly dilated in apical third; apex very blunt, apical portion forming a spoon-like structure with strongly extended walls. Endophallus armature spatulate, poorly sclerotized, located in the apical third of the median lobe. Parameres rather wide, gradually curved, with broadly rounded apex bearing 4–5 apical setae; left one slightly longer, with a distinct ventral apophysis.

Sexual dimorphism. The two known members of the genus do not reveal significant sexual dimorphism in morphometric characters. Nonetheless, the females are, on average, marginally larger, their appendages shorter, eyes smaller; only the length of the antennae in relation to the elytral length being significantly lesser (p<0.05 according to the Mann & Whitney U -test).

Comparative notes. Some characters of the new genus are intermediate between those of Queinnectrechus and Dactylotrechus, for example, the elytral chaetotaxy is characterized by presence of one additional setiferous pore in the exterior series (approximately on site of stria 5) and by transitive position of the preapical pore. Other character states, such as the fixed normal number of the discal setiferous pores in the interior series and the male genital structure seem to be unique within this groupe of trechines.

The genus Puertrechus gen. n. differs from Dactylotrechus in having only one anterolateral pore on the pronotum, entire lateral border of the latter, only one outer setiferous pore of elytra, and the inner row always consisting of three setiferous pores, typical of most Trechines in contrast to varying number observed in members of both Queinnectrechus and Dactylotrechus. Apart from the latter character, members of Puertrechus gen. n. differ from those of Queinnectrechus in presence of the preapical pore (although slightly displaced anteriad) and exterior pore on the elytra, the entire lateral border of the pronotum and shorter tempora.

The location of the first umbilicate setiferous pore in Puertrechus gen. n. is worth to be noted. Both known species show a clear tendency to a non aggregated condition, which is most noticeable in Puertrechus mengsaensis sp. n. In some specimens of this species, umbilicate pore 1 is so strongly displaced inward and backward that is often located only marginally before the level of the second umbilicate pore. Such a condition is considered to be primitive and is rather common among the cave-dwelling troglobitic species but rather unusual for the humicolous trechines ( Jeannel, 1928).

Apart from the external characters, the new genus has distinct male genitalia ( Figs. 8–9 and 13–14 ): the median lobe rather small and thin, markedly curved, its apical portion modified in a spoon-like structure with expanded and deflexed upward margins, the ventral surface in proximal half with a flattening or even impression, which is carinate laterally; the endophallus armature spatulate and poorly sclerotized.

Derivatio nominis. The generic epithet refers to the name of the geographic area Pu Er (or Pu-Erh) located in southern Yunnan, China.

Distribution. The two species of this genus originate from the two isolated small mountain ranges situated not far from the Chinese boundary with Myanmar, southwestern Yunnan (see Fig. 15 ).

Figures

FIGURE 15. Distribution of Puertrechus species. 1 (black circle) — Puertrechus daxueshanicus gen. n., sp. n.; 2 (white circle) — Puertrechus mengsaensis gen. n., sp. n.

FIGURES 8 – 9. Male genitalia of Puertrechus mengsaensis gen. n., sp. n.: a—lateral view, b—dorsal view, c—parameres, d—genitalic sac.

FIGURES 13 – 14. Male genitalia of Puertrechus daxueshanicus gen. n., sp. n.: a—lateral view with parameres, b—dorsal view, c—genitalic sac.