Dicheirotrichus (Trichocellus) subangularis, Abak & D.W, 2006

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 : 724-725

Dicheirotrichus (Trichocellus) subangularis spec. nova ( Figs 21-27 )

T y p e m a t e r i a l: Holotype: Kazakhstan, East Kazakhstan Province, flood plain of Chernyy Irtysh River, 12 km SW of Buran, 14.VI.1997, R. Dudko & V. Zinchenko leg. (ISEAN). Paratypes: 3, 3, same data as holotype (ISEAN, ZISP, cWR). 1: Mongolia: Chovd aimak, Bulgan gol, 10 km E Jarantaj, willow forest, 22.V.1974, R. Piechocki leg. (TMB). 1, "Siberia, Altai" (ex coll. V. Lutshnik) (ZISP).

D e s c r i p t i o n: Comparatively large, body length 4.9-5.4 mm, width 2.1-2.3 mm.

Colour: Dorsum largely brownish yellow, shiny; head on clypeus, frons, vertex medially and margins of mandibles rather strongly infuscate, almost black; pronotum either unicolorous or somewhat infuscate on each side of disc between median line and lateral margin; each elytron with dark brown or black longitudinal macula slightly variable in size but usually located on 2 nd interval medially and on 3 rd -4 th intervals behind middle, with distal margin of macula removed from elytral apex on distance about one-fifth of elytral length. Sutural intervals pale or more or less strongly infuscate between maculae. Underside of head and prosternum brown or dark brown, mesosternum, metasternum and abdominal sternites black. Epipleurae of pronotum and elytra brownish yellow, not infuscate. Legs, antennae and palpi more or less unicolorous, brownish yellow, but usually slightly lighter than dorsum (at most antennae scarcely infuscated from 4 th antennomere). Pubescence yellow.

Head: Medium sized (WHmax/WP = 0.74-0.78; WHmin/WP = 0.56-0.60), coarsely and irregularly punctured almost throughout (clypeus usually only externally), with more sparse punctures on frons and vertex. Each puncture bearing a short seta. Eyes large, nearly hemispherical, separated from buccal fissure by distance much less than width of first antennomere. Tempora short, slightly convex. Clypeus distinctly depressed along apical margin. Labrum with almost straight apical margin. Dorsal microsculpture visible on clypeus apically, and on areas under and behind eyes; consisting of fine more or less isodiametric meshes. Mandibles acute at apices. Antennnae moderately long, extending beyond elytral base approximately up to one fifth of elytra, with middle antennomeres about 1.8-2.0 times as long as wide.

Pronotum ( Fig. 21 ): Weakly convex, flattened basally, relatively narrow, 1.28-1.38 times as wide as long, widest in apical third. Its sides basally almost rectilinearly converging posteriad. Apical margin weakly emarginate, almost straight medially, bordered only laterally. Basal margin rounded medially, oblique laterally, with distinct bead along oblique portion on each side, approximately equal to apical margin, much narrower than elytral base, and clearly ciliate on basal ridge. Apical angles not protruding anteriad, usually slightly blunt at apices. Basal angles obtuse, with sharp apices, each bearing a long seta (latter broken off in many specimens). Lateral furrows narrow throughout and lateral depressions not developed. Basal foveae somewhat large and narrow, reaching basal pronotal margin basally and curved slightly to sides apically, separated from each other and from sides by convexities. Pronotal surface almost throughout punctured and pubescent, more coarsely and densely along margins, more finely and sparsely in central portion. Punctures confluent and particularly coarse in basal foveae. Each puncture bearing a short seta. Dorsal microsculpture on disc invisible, sometimes strongly evanescent meshes poorly recognizable only along sides, mainly near apical angles, and basally.

Elytra: Moderately convex, 1.45-1.52 times as long as wide, 2.87-3.07 times as long and 1.47-1.55 times as wide as pronotum, slightly widened posteriad (widest behind middle), and rounded at sides. Humeri prominent, evenly rounded. Subapical sinuation weak. Sutural angle narrowly rounded at apex. Basal bead weakly sinuate and arcuately curving inside humerus up to lateral margin. Parascutellar setigerous pore puncture present. Third interval just before apical third with a discal setigerous pore near second stria. Posterior group of umbilicate series consisting of eight setigerous pores. Striae unpunctured, on disc slightly impressed throughout, along elytral sides finer, superficial; 7 th stria obliterate at basal bead. Intervals largely weakly convex, almost flat apically, weakly narrowed posteriad. Puncturation of intervals on elytral disc rather fine, with two, sometimes three, punctures in a transverse row across each interval at middle. Each puncture bearing a short, posteriorly inclined seta. Microsculpture consisting of fine, more or less isodiametric meshes, in male visible apically, basally, and on 3-4 lateral intervals, in female meshes extended more widely, but generally absent or strongly evanescent in central part of elytral disc.

Wings: Fully developed.

Ventral surface: Metepisterna ( Fig. 22 ) long and narrow, strongly narrowed posteriad. Anal sternum rounded at apex, with one pair of marginal setae in male and two pairs in female.

Legs: Fifth tarsomere with two, sometimes three, pairs of ventro-lateral setae. Metatarsus slender, a little longer than width of head across eyes, with tarsomeres almost parallelsided; first metatarsomere notably longer than second but shorter than second and third together. In male protarsi ( Fig. 23 ) moderately dilated and with biseriate vestiture ventrally; mesotarsi simple.

Female genitalia ( Fig. 27 ): Hemisternite asymmetrical, without spines or setae. Basal stylomere slightly widened apicad, also without spines or setae. Apical stylomere weakly arcuate, moderately long, with a short peg-like seta on outer ventral margin before middle.

Median lobe of aedeagus ( Figs 24 -28): Weakly and rather evenly arcuate, with nearly straight apical portion (lateral aspect); sides more or less roundly converging to acute apex, with hardly recognized sinuations medially (dorsal aspect). Internal sac with symmetrical pattern of tiny spines, without larger spines or teeth.

D i s t r i b u t i o n: This new species is known from East Kazakhstan and West Mongolia. It ranges probably along southern macroslopes of the Altai Mountains.

E t y m o l o g y: The species epithet is based on the Latin prefix sub - and the Latin word angularis meaning ‘angular’, referring to the rather distinct basal angles of the pronotum of the new species.

R e m a r k s: D. subangularis spec. nova is easily recognizable by the rather large body, the somewhat pale coloration, the shape of pronotum with distinct basal angles, the punctured elytra, the comparatively strongly dilated male protarsi, and the genital characteristics. In the habitus, particularly in the shape of the pronotum, this new species is similar to D. angularis and D. latimanus spec. nova, but distinctly differs from them in having the body larger, the elytra relatively wider, the general coloration paler (always with pale elytral apex and epipleurae), the dorsal puncturation more fine, the metatarsi more slender and the apical lobe of the aedeagus (in dorsal view) more strongly narrowed apicad, with a more acute apex, and with a nearly symmetrical pattern of tiny spines in the internal sac. The male protarsi of D. subangularis spec. nova are only a little less dilated than those of D. angularis , but much narrower than those of D. latimanus spec. nova.

Figures

Figs 21-27: Dicheirotrichus (Trichocellus) subangularis spec. nova. (21) Pronotum. (22) Left metepisternum. (23) Male protarsus. (24-26) Median lobe of aedeagus (holotype), (24, 25) dorsal view and (26) lateral view. (27) Hemisternite and stylus. Scales = 0.5 mm (A: Fig. 21; B: Figs 22- 23; C: Figs 24-27).