Dicheirotrichus (Trichocellus) stenothorax (KABAK & KATAEV 1994)

Abak & D. W, 2006, Three new species of the subgenus Trichocellus GANGLBAUER 1891 of the genus Dicheirotrichus JACQUELIN DU VAL 1857 from the East Palaearctic, with description of the male of D. stenothorax (KABAK & KATAEV 1994) (Coleoptera, Carabidae), Linzer biologische Beiträge 38 (1), pp. 717-729 : 718-719

Dicheirotrichus (Trichocellus) stenothorax (KABAK & KATAEV 1994) (Figs 7-10)

Trichocellus (s. str.) stenothorax KABAK & KATAEV 1994: 296 .

T y p e m a t e r i a l: Holotype:, Kirghizstan , western portion of Kungey Alatoo , Boom Gorge, Chilbili River, 19.V.1990, I. Kabak leg. ( ZISP).

A d d i t i o n a l m a t e r i a l:

R u s s i a: Volgograd Prov.: 1, Gornaya Polyana, Vodnyj vill. env., reedbed, near water, 8.VII.1983, E. Komarov leg. ( ZISP) ; 10 specimens (and), Elton Lake env., 24.IV.1989, E. Komarov leg. (cKOM; ZISP) ; 2, 1, Elton Station env., bed of dry freshwater lagoon, under stones, 18.IV.1985, E. Komarov leg. ( MPU). - Samara Prov.: 1, Siniy Syrt, 13 km SSW of Kostino, right bank of Rostasha River , slope of balka, 28.VII.-28.VIII.1993, Smelyanskij leg. ( ISEAN) .

K a z a k h s t a n: 1, Transili Alatau , Zhenishke env., 1600 m, 18.VI.1988, M. Childibaev leg. (cIKAB) ; 1, Central Kazakhstan, Sultan-Keldy, 29.V.1980 (cIKAB) ; 1, 3, Dzhanibek env., 12.IX.2001, J. Miatleuski leg. (cWR, ZISP) .

A d d i t i o n a l d e s c r i p t i o n: Body length 4.1-4.6 mm, width 1.6-1.8 mm. Male: As in female, dorsal microsculpture recognizable only at elytral apex, meshes more or less isodiametric. Apical sternum with two marginal setae. Protarsi (Fig. 8) weakly dilated, their 1 st -4 th tarsomeres approximately as long as wide, each with biseriate vestiture ventrally. Mesotarsi simple, not dilated. Median lobe of aedeagus (Figs 9-10) bent just after basal bulb, with almost straight apical portion (lateral aspect); sides rounded in basal half, more or less rectilinearly converging to acute apex (dorsal aspect); internal sac with symmetrical pattern of tiny spines, and besides, with two (sometimes connected) groups of larger spines apically.

Proportions (based upon 5 males and 8 females): WP/LP = 1.23-1.34; LE/WE = 2.88- 3.33; WE/WP = 1.46-1.55; WHmax/WP = 0.77-0.81; WHmin/WP = 0.61-0.65.

D i s t r i b u t i o n: Steppe zone from Volga to northern Tien Shan.

E c o l o g y: AccordingtoKALYUZHNAYA et al. (2000), in the Lower Volga area the beetles occur in wet saline habitats with rich vegetation near water.

R e m a r k s: This species was described from a single female collected in the Boom Gorge, in the northern Tien Shan, and more recently, based on our determinations, it was recorded without any taxonomic remarks and additional characteristics from the Lower Volga area of Russia and Kazakhstan ( KRYZHANOVSKIJ et al. 1995; KALYUZHNAYA et al., 2000; KOMAROV 2002; JAEGER & KATAEV 2003). Unfortunately, males from the Tien Shan are still unknown and the male characteristics of D. stenothorax listed above are based on specimens from European Russia and western Kazakhstan. It should be noted, however, that the specimens from Russia and Kazakhstan slightly differ from the holotype in some external characters and may really represent a geographic form or even a separate species if it can be shown that their male genitalia are also different. The specimens from European Russia and Kazakhstan are scarcely larger (4.2-4.6 mm) than the holotype (4.1 mm), their metepisterna (including those of the female from the Transili Alatau) are longer (Fig. 7) and the pronotum is sometimes wider and with more rounded sides. At the moment we prefer to treat them as conspecific, but examination of males from the Tien Shan, particularly from the type locality, is required to verify this treatment.

By the male genitalia with two groups of larger spines in the internal sac, D. stenothorax is somewhat similar to D. obscuricollis (REITTER 1899) which, however, clearly differs from the former in having the pronotum almost throughout black and with much more fine and sparse puncturation on disc. In addition, the median lobe of the aedeagus of D. obscuricollis is a little more arcuate, more evenly rounded at sides and with a different pattern of tiny spines in the internal sac. In the external characters, the specimens of D. stenothorax , particularly from European Russia and Kazakhstan with their long metepisterna, are very similar to small specimens of D. discolor (FALDERMANN 1836) and in some cases the discrimination of females is very difficult. D. stenothorax may be distinguished from D. discolor by, on average, smaller body, longer pronotum, and shorter, more sparsely punctured elytra with lower number of umbilicate pores in the posterior group of the series (usually seven, more rarely six or eight, in D. stenothorax , and eight, rarely seven, in D. discolor ). The median lobe of the aedeagus of D. discolor differs notably from that of D. stenothorax in having the sides more evenly rounded and the internal sac has a different pattern of tiny spines and is without any spiny patches in the apical portion of the median lobe. The geographical ranges of both species seem not to be overlapping and this fact also aids determination. D. discolor with its two subspecies, the nominotypical one and D. d. punctidorsis (REITTER 1899), is distributed mainly to the south of the range of D. stenothorax , from Transcaucasia through the deserts of Middle Asia to western China.