Trechus uygur, Deuve, 1993

Belousov, Igor A. & Kabak, Ilya I., 2019, New species of the genus Trechus Clairville, 1806 from the Chinese Tien Shan (Coleoptera: Carabidae), Zootaxa 4679 (1), pp. 47-68 : 48-49

The uygur species group

This clearly defined species group includes Trechus species characterized by the following combination of characters: large size (over 4.3 mm), rather dark, reddish to brownish color of the upper side, elongate body shape, slender appendages, large head with small subconvex eyes and tempora long and regularly convex; supraorbital pores located in lines clearly convergent posteriad; pronotum subcordiform, normally with nearly straight convergent sides in posterior half and acute hind angles produced backwards and outwards; elytra flattened, ovate or ovate-oblong, with maximum width more or less behind their mid-length, markedly wider at level of preapical sinuation than at humeral level; each elytron rounded separately at the apex, umbilicate series well-aggregated, preapical pore located in the apical cross of striae 2 and 3 at level clearly behind anterior termination of apical striole; aedeagus very large, seldom medium-sized, slightly to markedly S-shaped, with apical disc or button more or less oblique; lamella average to large; sagittal aileron lacking or developed; endophallus armature variable in size and shape, without heavily sclerotized pieces, often consisting of two hyaline structures, at least, one of which in ventral position; parameres long, slender, left one with more distinct ventral apophysis, each paramere bearing 5–6 apical setae.

Within Central Asia, this species group does not show clear affinities with any other known species groups of the genus. Their large size, dark color, large S-shaped median lobe of the aedeagus with button-like apex, and distribution suggest a certain similarity of members of the group with T. gitzeni Belousov & Kabak, 2001 . However, the latter species differs in its darker, piceous color, wider ovate elytra with striae more markedly impressed and roughly punctate as well as in its much larger eyes. In contrast to members of the uygur species group associated with melting snow in the alpine zone, T. gitzeni has been found on banks of rivers in the forest zone. Therefore, the relationships of T. gitzeni and members of the uygur species group need further investigation. In their mode of life and general appearance, species of the uygur group resemble, to some extent, stout Asian species of the genus Duvalius Delarouzée, 1859 , sharing the following characters: large head, small eyes and long tempora, oblong-ovate elytra with more or less rounded humeri and long legs and antennae, though the Duvalius species differ in having the pronotum much more cordate, appendages much longer and paler coloration of body.

All of the known species inhabit the basins of the Kash and Kunges rivers, the easternmost tributaries of the Ili River, Xinjiang, China ( Fig. 9 ). Interestingly, species of the group seem to be strictly allopatric to species of Duvalius occurring in neighboring areas.

Species of the group are humicolous and mostly inhabit stony biotopes near melting snow in the alpine zone at elevations between 3000 and 3600 m, though they can sporadically be found at lower elevations.

Figures

FIGURE 9. Collecting sites of Trechus species of the uygur group. Yellow rhomb—T. sinus Belousov & Kabak, 2001; red rhomb—T. arshanicus Belousov & Kabak, 2001; yellow square—T. uygur ssp. kuytunicus Belousov & Kabak, 2001; red square—T. uygur ssp. uygur Deuve, 1993; yellow triangle—T. torgaut sp. n.; red triangle—T. tsanmensis sp. n. Locality numbers—as in the “Material” section; those for collecting sites of T. arshanicus and T. sinus—see Belousov & Kabak (2001).