Oxytrechus alexei, Delgado & Ruiz-Tapiador, 2019

Delgado, Pedro & Ruiz-Tapiador, Ildefonso, 2019, Two new species of Oxytrechus Jeannel, 1927 (Coleoptera, Carabidae, Trechini) from Peru, Zootaxa 4565 (1) : -

Oxytrechus alexei n. sp.

( Fig. 3 and 4 )

Type locality. Peru, Puno, Cordillera Carabaya, Abra Oquepuño , 4888 m, 14°10’42’’ S 70°19’46’’W .

Type series. Holotype ♂, Perú, Puno, Cordillera Carabaya, Abra Oquepuño , 4888 m, 14°10’42’’ S 70°19’46’’W, 25.IV.2017, leg. P. Delgado, ( MNCNM).

Paratypes: 2 ♂ 3 ♀, same data as the holotype (1 ♂ and 2 ♀ ( CPD), 1 ♂ and 1 ♀ ( CIRT). 14 ♂ 8 ♀, Perú, Puno, Cordillera Carabaya, Abra Oquepuño , 4888 m, 14°10’42’’ S 70°19’46’’W, 28.IV.2017, leg. P. Delgado (10 ♂ and 6 ♀ ( CPD), 3 ♂ and 2 ♀ ( CIRT) and 1 ♂ ( MNCNM).

Description. Total length (ABL): 2.05–2.14 mm ♂, 2.14–2.17 mm ♀. Micropterous, body light brown with paler, testaceous appendages. Smooth and shiny integument, glabrous, with visible microsculpture.

Head elongated (HW /HL = 0.70–0.78); totally covered by microreticulation, more intense close to the supraorbital sulci; temples of same length as the eyes, frontal sulci deep and complete; eyes not very large, flat and approximately of the same length as the genae; two supraorbital setae in each side. Antennal length (TLA) between 0.89–0.91 mm., the apical antennomere clearly exceeding the base of the elytra. Antennomeres markedly pubescent, with the exception of the scape where pilosity is scarcer.

Pronotum gently transverse (PW / PL = 1.22–1.29), convex, with maximum width in the anterior third of the length. Lateral margins slightly arched through their length, subrectilinear posteriorly, gently sinuate before the posterior angles, which are obtuse and prominent; anterior angles are not projected forwards; basal peduncle prominent; median sulcus and basal impressions softly marked. Two lateral setae at each side, the anterior one just before the widest point, the posterior one before the posterior angle. Microsculpture more noticeable near the lateral margins and progressively less marked toward the disc region.

Elytra ovoidal and convex (EW / EL = 0.70-0.76), fully covered by microreticulation; lateral groove wide and flattened. Shoulder region evident marked. Internal striae of elytra weakly marked, absent in the apical region; external striae not visible; without trace of basal striola. Apex of elytra softly curved, almost substraight. Scutellar pore clearly marked. Two discal pores present, the first one located in the basal fifth of the total length and the second, just behind the half of the elytra. The umbilicate series is regular and corresponds to the usual model for the genus. External pore of the apical group absent.

Legs short and slim; light testaceous, with femora slightly darker proximally. Protibial sulcus complete but superficial, straight metatibiae. First two protarsomeres asymmetrically dilated in males.

Aedeagus (fig 4) strongly arched, with an oblique bulb base, lacking sagittal carina. Apex of median lobe slightly arched downwards, obtuse, progressively attenuated and with a bottleneck before the extreme, which is ovoid. Internal sac without copulatory pieces, only with small internal scales in distal position. Parameres with four setae at their distal ends.

MAP 1. Geographical setting of genus Oxytrechus in Peru 1) O. cyathiderus , 2) O. gitzeni , 3) O. paredesi , 4) O. juani n. sp., 5) O. alexei n.sp.

Differential diagnosis. The structure of aedeagus in O. alexei n. sp. shows clear differences with the aedeagi of the other Peruvian species. It is distinguishable from O. paredesi , O. gitzeni and O. juani n. sp. by the shape of the apex of aedeagus, clearly different. Moreover, O. paredesi , O. gitzeni and O. juani n. sp. show copulatory pieces in the internal sac, not observed in O. alexei n. sp. In the case of O. cyathiderus the general structure of aedeagus is more akin to that of O. alexei n. sp. but in the former, aedeagus is long and barely curved ventrally, while in O. alexei n. sp. the ventral curve is much more pronounced and, overall, the aedeagus is shorter.

Within the other species of the genus, only the species described from Colombia, O. silvanus Mateu, 1991 , shows an aedeagus with a general morphology similar to O. alexei n sp. However, in the case of O. silvanus , the narrowing of the distal extreme of the median lobe is much more marked than in O. alexei n. sp., and O. silvanus has a sagittal carina in the base of the bulb, absent in O. alexei n. sp.

Etymology. This species is named after Alex Delgado Sosa as a sign of gratitude for his effort and perseverance.

Ecology. Currently, O. juani n. sp. and O. alexei n. sp. are only known from their type localities. They seem to be highly adapted to the conditions of the agroecological area of humid Puna that occur in Carabaya mountain range, characterized by high elevation, very low temperatures, annual rainfall between 800–1000 mm and scarce vegetation, mainly represented by Stipa ichu along other grasses ( Poaceae ) such as Aciachme pulvinata and Antochloa lepidula .

Figures

FIGURE 3. Oxytrechus alexei n. sp. Habitus, male (holotype). Scale bar: 0.5 mm.

FIGURE 4. Male genitalia of O. alexei n. sp., lateral view. Scale bar: 0.1 mm.