Oxytrechus cayambeensis, Quéinnec & Ollivier, 2019

Quéinnec, Eric & Ollivier, Eric, 2019, Two new Oxytrechus species from Ecuadorian páramo (Coleoptera, Carabidae, Trechinae), Zootaxa 4646 (1), pp. 55-66 : 61-64

(b) Oxytrechus cayambeensis n. sp.

(figs. 4, 5)

Type locality: Ecuador, Southwestern slope of the Cayambe volcano (Pichincha Province), around 4400 m.

Type series: Male holotype labelled: „ Ecuador, Pichincha Province, Cayambe volcano, south-west slope, Polylepis sp. grove , alt. 4400 m, 0°00’37’’N 78°01’28’’W, 22.VII.2018, E. Quéinnec & R. Chiori leg.“ (white label, p)/„Holotype Oxytrechus cayambeensis sp. nov. Quéinnec & Ollivier des.“ (red label, p), CEQ ; Paratype: 1F, same data as holotype (white label, p) but labelled: „ Paratype Oxytrechus cayambeensis sp. nov. Quéinnec & Ollivier des.“ (red label, p), in coll. MNHN .

Diagnosis: An Oxytrechus of large size (LT = 3.5–3.6 mm; 3.5 mm for male holotype). Body fairly elongated and broad, with relatively small head and long legs. Apterous. Head, pronotum and elytra shiny blackish brown; elytra slightly iridescent. Clypeus, labrum, palpi, antenna and legs bright reddish brown.

Head small, subquadrate (HW/HL = 0.67/0.67 = 1 in male holotype and female paratype) and moderately depressed above, with deep entire frontal furrows which are sub-angulate at middle and moderately divergent in front; both frons and supraorbital areas gently convex, the latter with a foveola on each side at the root of supraorbital seta; microsculpture distinct, consisting of coarse polygonal meshes which are mostly isodiametric on frons and supraorbital areas but transverse on vertex; eyes small but gently protruding though convex; genae glabrous, curved, about as long as eyes; neck wide; mentum gently emarginate at apex; mandibles long and slender; palpi short though fairly slender; antennae fairly long (LA = 1.93 mm in both sex) for a direct relative of O. globosus , reaching or extending a little beyond basal one-sixth of elytra, with segment two slightly longer than segments 3 and 4 each, as long segment 5 and only shorter than segment 6; antennal segments 7–10 each about three-sevenths as wide as long.

Prothorax. Pronotum transverse (PW/PL = 0.92/0.67 = 1.37 in male holotype; 1.35 in female) and convex, wider at about three-fifths from base and more strongly contracted posteriad than anteriad; microsculpture composed of very fine transverse lines partially forming very transverse meshes; sides sharply bordered and reflexed, particularly behind middle, moderately rounded in front, much so behind but not sinuate before hind angles, which are scarcely marked; anterior marginal seta situated before the widest part, the posterior one close to hind angle; apex either straight or slightly emarginate, with front angle slightly advanced though narrowly rounded; base nar- rower than apex, straight at middle but oblique on each side inside hind angle; median line sharply impressed, somewhat widening near base; apical transverse impression usually continuous though shallow at the median part and continuing on each side to near basal border; basal fovea not large and rather mal-defined; basal area uneven with marked longitudinal striations.

Pterothorax. Elytra ovate (EW/EL = 1.67/2.21 = 0.75 in male holotype; 0.77 in female), widest about fourninths from base, well convex at the sides and in apical part but more or less depressed on the disk; the ratio of the width of the elytra to that of pronotum 1.79–1.81 (mean 1.80); microsculpture sharply impressed, consisting of polygonal meshes which are usually wide; shoulders distinct though rounded; prehumeral borders fairly long and moderately curved; sides rather widely reflexed, moderately arcuate from shoulders to apices which are rounded, each with a slight preapical emargination; striae completely obsolete, even in the basal part and apical one; sutural stria scarcely evident. Scutellar striole slightly reduced but discernable, very short, nearly straight; apical carina hardly visible; two setiferous dorsal pores, fovea-like, on the putative site of stria 3, the anterior one at the 3/10–3/8 from base, the posterior one just on the middle; humeral group of umbilicate series with the four pores equidistant, first pore of the middle group behind the level of the second discal pore; preapical pore close to the apex, at the level of the 8th pore of the umbilicate series; internal apical pore not detected.

Legs relatively long though fairly stout; protibiae straight, moderately dilated towards apices, scarcely pubescent on the anterior face, each with a groove on the external face and also with a very shallow groove along the inner side of the external one; tarsi fairly slender, tarsal segment 4 with a long ventral apophysis in pro- and mesotarsi; two proximal segment of each protarsus widely dilated in male, and well produced inwards at apices.

Ventrites. Ventral surface smooth, but covered with microscopic pubescence perceptible only under high magnification; anal sternite provided with a pair of sexual setae in male, with two pairs in female.

Aedeagus (fig. 5). Male genital organ fairly large, elongate but slightly sclerotized. Aedeagus fairly slender and hardly arcuate behind middle, with rather large basal part, which is straight, heavily sclerotized ventral side, and then bent towards the dorsal side; lateral sides of basal orifice semi-circularly emarginated; sagittal aileron very large, elongate and roundly dilated at apex; viewed laterally, apical part regularly attenuated, slightly produced and turn up at the extremity, which is rounded; viewed ventrally (fig. 5B), median lobe subparallel, apical part slightly blunt, with conical extremity; viewed dorsally (fig. 5C) apical part seems to be slightly widening and then attenuated towards apex. Inner sac armed with an elongated than the right, each provided four, rather short setae at apex.

Derivatio nominis: The specific epithet refers to the type locality of the new species, the Cayambe volcano.

Distribution: Localized on the Eastern Cordillera on the Southwestern slope of Cayambe volcano.

Diagnostic characters: The Oxytrechus cayambeensis n. sp. is morphologically distinct from O. onorei Allegro et al., 2008 with whom it lives in sympatry. It differentiates itself from this species by its much larger size (3.5–3.6 mm versus 2.88–3.14 mm for onorei ), its very different morphology with wider elytra, in a regular oval, and by its conformation to the aedeagus. O. cayambeensis is also divergent from O. lallemandi shares similarities with O. onorei . O. cayambeensis species is also close to O. globosus by its general conformation, its size and its elytral shape. Nevertheless, O. cayambeensis’ head is smaller than globosus ’, the eyes are smaller and not prominent, the pronotum is more transverse, with a less convex surface; its sides present a maximal width at the 3/5 th from base (by the middle for O. globosus ). The elytral striation is far more pronounced for O. globosus in which the location of the three first striations can be distinguished (the elytral surface is smooth for O. cayambeensis ). On the other hand, the aedeagus of the two species is of substantially different general shape (cf. Moret, 2005, fig. 91, for O. globosus ). What is quite surprising is that the aedeagus of O. cayambeensis presents some analogies with those of O. moreti and O. zoiai but is far more robust: the sagittal blade is wider and stretched out; the median lobe progressively diminishes around the apex. The habitus of O. cayambeensis differs from O. zoiai and O. moreti by its imposing size (3.5–3.6 mm versus 2.9–3.0 mm for moreti and 3.0– 3.3 mm for zoiai ) and by its quite different, broader, and more globose form.