Trechisibus sciakyi, Allegro, Gianni & Giachino, Pier Mauro, 2016

Allegro, Gianni & Giachino, Pier Mauro, 2016, Nine new Trechisibus species from Peru and Argentina (Coleoptera: Carabidae: Trechinae), Zootaxa 4193 (1), pp. 49-72 : 63-65

Trechisibus sciakyi n. sp.

( Figs. 9 a, 9b, 9c, 9d, 18)

Type locality. Argentina, Neuquen, Pen. Quetrihué.

Diagnosis. A Trechisibus species 4.75–5.20 mm long, dark brown and shiny; legs and lateral border of elytra reddish brown; mouth parts paler; antennae darkened from the 2nd antennomere. Hind angles of pronotum usually right, slightly protruding outwards. Elytra oval, moderately depressed on disc, with 2 discal setigerous punctures (in addition to the preapical pore) on the 3rd stria, the first at about 1/5 from base and the second at middle or just before middle. T. sciakyi n. sp. is distinguished from all other Trechisibus species distributed in the southern Andean Cordillera by the very peculiar morphology of the median lobe of aedeagus, which is very short and stocky ( Fig. 9 a).

Type Series. HT ♂, Argentina, Neuquen, Pen. Quetrihué, 12.II.1998, legit Riccardo Sciaky (CSc). PTT: 5 ♂♂, same data as the holotype (CAl, CGi, CSc).

Description. Habitus as in Fig. 9 a. Overall length of the HT ♂ (from labrum to apex of elytra) 5.20 mm. Body dark brown, obovate, shiny. Microsculpture very superficially impressed on pronotum and elytra, markedly impressed on head. Legs and lateral border of elytra reddish brown; mouth parts paler; antennae with the 1st article reddish brown, the others darkened. Brachypterous.

Head moderately large, eyes large and feebly convex; temples convex and delicately pubescent, shorter than eyes. A microsculpture in isodiametric meshes markedly impressed on whole upper surface of head. Clypeus with two apical setae on each side; labrum transverse, 6-setose, distinctly excavate at apex. Frons between eyes convex with a small depression on vertex. Antennae moderately long, reaching the basal 4th of elytra.

Pronotum convex on disc, transverse (width/length = 1.39), with base wider than anterior margin ( Fig. 18 ). Disc almost shiny and microsculpture nearly absent except at sides and near fore margin. Sides rounded for most of length, shortly sinuate before hind angles; basal margin almost rectilinear, hardly sinuate at sides. Front angles feebly prominent; hind angles usually right, sometimes slightly protruding outwards. Mid longitudinal line distinctly impressed between the submarginal sulci, deepened towards base. A wide basal impression on each side, separated at middle by the mid convexity of the base. Lateral border narrow and only slightly broadened towards hind angles; anterior and posterior margins bordered only at sides. Two lateral setae on each side, one at hind angles (moved a little forwards from the angle) and one at about 2/3 from base.

Elytra oval (length/width=1.30), feebly depressed on disc. Microsculpture nearly absent. Shoulders rounded with humeral angle indistinct. The basal margin interrupted in correspondence with the 4th stria. A short scutellar stria is present, as well as a juxtascutellar pore near base, in correspondence with the 2nd stria. Sides moderately rounded; lateral border narrow over the whole length, reddish brown and distinctly contrasting in colour with the darker elytra. Two discal setigerous punctures in small and superficial foveae on the 3rd stria, the 1st at basal 5th of elytra and the 2nd at middle or just before middle; the punctures can divert the 3rd stria linearity; preapical pore at about middle of the recurrent striole. Umbilicate series of 4+2+2 punctures, with groups widely spaced from each other. All striae moderately and equally impressed, distinct from base to apex; the 8th stria deeply impressed in the posterior third. Intervals nearly flat. Elytral apex broad and rounded. The recurrent striola moderately long and arcuate.

Legs slender. Protibiae straight and externally distinctly furrowed. Tarsi pubescent on the upper side. The 1st and 2nd male protarsomeres asymmetrically dilated.

Median lobe of aedeagus short and, in lateral view, very stocky. The inferior edge nearly straight and bent downward before apex ( Fig. 9 b); apical blade very short and, in dorsal view, widely triangular, blunt at extreme apex ( Fig. 9 c). The internal armature is made by different sclerotized pieces with two longitudinal bundles of squamose teeth, the first near the base and the second in a subapical position ( Fig. 9 c). Parameres wide and short, almost equally long, each provided with 4 apical setae ( Fig. 9 b).

Etymology. This species is dedicated to its collector, Riccardo Sciaky, as a sign of gratitude for giving us this material in study and as a sign of esteem for his important contribution to the knowledge of Carabidae .

Distribution and habitat. At present Trechisibus sciakyi n. sp. is only recorded from the type locality. The specimens of the type series were collected at about 800 m a.s.l.

Relationships. At the present state of knowledge, the phylogenetic affinities of Trechisibus sciakyi n. sp. are unclear. No other Trechisibus species from the Patagonian Region (or from the whole southern Andean Cordillera) have a similar aedeagus. Anyway, despite the strong differences in the morphology of the aedeagus, this species shares many external morphological features with Trechisibus striatus n. sp., Trechisibus brevis n. sp. and Trechisibus longipenis n. sp.

Figures

FIGURE 9. Trechisibus sciakyi n. sp. HT: habitus (a); median lobe of aedeagus in lateral view (b); median lobe of aedeagus in dorsal view (c).

FIGURES 17 – 21. Pronotum of Trechisibus: striatus n. sp. HT (17); sciakyi n. sp. HT (18); brevis n. sp. HT (19); longipenis n. sp. HT (20); parvulus n. sp. HT (21).