Trechisibus huascarani, 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 : 50-54

Trechisibus huascarani n. sp.

( Figs. 1 , 2 a, 2b, 2c, 2d, 3, 13)

Type locality. Peru, Dip. Ancash, Punta Olímpica 4,550 m, laguna.

Diagnosis. A Trechisibus species 3.92–4.37 mm long, moderately shiny, brown with head a little darker; legs and antennae reddish-brown. Hind angles of pronotum obtuse. Elytra oval-elongate, depressed on disc, with 4–5 setae on the 3rd stria (in addition to the preapical seta) and 2–3 on 5th. It can easily be distinguished from T. amesi Etonti & Mateu, 1992 , a very similar species recorded from the Cordillera Blanca with more than three discal setae on the 3rd elytral stria, by the presence of 2–3 setae on the 5th stria as well (absent in T. amesi ) and by the shape of the median lobe of the aedeagus, which is not inferiorly bulging before apex in lateral view (distinctly bulging in T. amesi ). Trechisibus curtii n. sp., a species recorded from Huánuco also showing more than three discal setae on the 3rd elytral stria, is very different from T. huascarani n. sp. in external morphology and morphology of the aedeagus.

Type Series. HT ♂, Peru, Dip . Ancash, Punta Olímpica, m 4,550, 5.VII.2008, legit G. Allegro (CAl). PTT: 8 ♂♂ 5 ♀♀, same data as the holotype (CAl, CCa, CGi, CSc, BMNH) .

Description. Habitus as in Figs. 1 and 2 a. Overall length of the HT ♂ (from labrum to apex of elytra) 4.03 mm (PTT ♂♂ 3.92–4.37, ♀♀ 4.02–4.30 mm). Elytra brown, head black-brown and pronotum reddish-brown, moderately shiny. Microsculpture in transverse meshes superficially impressed on elytra, on pronotum visible only near hind angles. Antennae, tibiae and mouthparts reddish, femora a little darker. Brachypterous.

Head large and stout, eyes small and moderately convex; temples convex and delicately pubescent, as long as eyes. Clypeus with two apical setae on each side, the inner one shorter and thinner; labrum transverse, 6-setose, excavate at apex. Frontal impressions arcuate and deeply impressed. Frons between eyes convex, smooth and shiny. Antennae long, reaching the basal fourth of elytra.

Pronotum moderately convex on disc and explanate near hind angles, transverse (width/length = 1.41), with base as wide as the anterior margin ( Fig. 13 ). Disc smooth and shiny, the microsculpture distinct only near hind angles, in the explanate area from the basal impression, which is wide and impunctate, to the lateral margin. Sides rounded in the fore half and linear in the basal half, with maximum width at about 3/4 from base; base subrectilinear. Front angles not prominent; hind angles marked and obtuse. Mid longitudinal line distinctly impressed between the submarginal sulci. Lateral margins wide and broadened towards base; anterior and posterior margins bordered only at sides. Two lateral setae on each side, one at hind angles and one about 4/5 from base.

Elytra oval (length/width=1.40), fairly convex but depressed on disc. Microsculpture in transverse meshes, superficial in both sexes. Shoulders broadly rounded. The basal margin interrupted in correspondence with the 5th interval. Scutellar stria absent. A juxtascutellar pore is present near base, in correspondence with the 2nd stria. Sides moderately rounded; lateral border narrow. 4–5 setigerous punctures on the 3rd stria in addition to the preapical puncture, the 1st at basal 6th, the others more or less regularly spaced; 2–3 setigerous punctures also on the 5th stria, usually in the basal half, but sometimes the 2nd or 3rd just behind middle. Umbilicate series of 4+2+2 punctures, with the groups widely distanced from each other. Only striae 1st–5th superficially impressed and obliterated at base and towards apex (the 1st more impressed than 2nd–5th), the others hardly visible. Intervals flat, the 1st narrower than the followings. Elytral apex rounded, with sutural angles of elytra divergent. The recurrent stria long and distinctly impressed, with a remarkable apical carina.

Legs slender. Protibiae nearly straight and not externally furrowed. Tarsi pubescent on the upper side. The 1st and 2nd male protarsomeres asymmetrically dilated.

Median lobe of aedeagus stout ( Fig. 2 b), in lateral view the inferior edge rectilinear towards apex, which is thin, short and, in dorsal view, broadly rounded ( Fig. 2 c). The internal armature is peculiar as it is made by two overlapping sclerotized pieces, one in upper and one in lower position, long and sinuous, joining at apex ( Fig. 2 b). Parameres narrow and long, the left one longer than the right and as long as half of the median lobe, each provided with 5–6 apical setae ( Fig. 2 d).

Etymology. Species name derived from the noun, in the genitive case, of Mt. Huascarán, the highest mountain in Peru (6,768 m), dominating the Huascarán National Park which includes the type locality.

Distribution and habitat. At present Trechisibus huascarani n. sp. is only recorded from the type locality. All specimens of the type series were collected under stones laying on humid soil near a lake (about 4,550 meters a.s.l.) below the Punta Olímpica Pass, in a glacial area characterized by coarse detritic sediments ( Fig. 3 ). It lives in syntopy with Trechisibus recuayi n. sp. and Blennidus (Agraphoderus) huascarani Allegro, 2010 , which are described from the same type locality.

Relationships. Trechisibus huascarani n. sp. is actually very similar to T. amesi , both in external morphology and in male genitalia (in particular in the copulatory piece), although these species can be easily distinguished by the characters mentioned here above in the diagnosis. The subgenus Trechisibiontes Etonti & Mateu, 1992 , created for T. amesi on account of the presence of four or more setae on the third elytral stria, was recently synonymized with Trechisibiellus ( Avon 2007) . Both species live in Cordillera Blanca, and they also share the habitat of high altitude glacial areas, as also T. amesi is recorded from the vicinities of a glacier (Pastoruri) at 4,850–4,950 meters a.s.l. Mainly due to the marked similarities in male genitalia, T. amesi and T. huascarani n. sp. probably deserve a their own species group.

Despite the presence of additional discal setae on the 5th elytral stria, which are also present in T. hornensis (Fairmaire, 1855) and T. curtii n. sp., T. huascarani n. sp. does not seem closely related to these species on account of marked differences in external morphology as well as morphology of the aedeagus.

Figures

FIGURE 1. Habitus of Trechisibus huascarani n. sp. (scale bar = 1 mm). Drawing by Gianni Allegro.

FIGURE 2. Trechisibus huascarani n. sp. HT: habitus (a); median lobe of aedeagus in lateral view (b); median lobe of aedeagus in dorsal view (c); parameres (d).

FIGURE 3. Peru, Dept. Ancash, Cordillera Blanca. The lagoon below the Punta Olímpica Pass (4,550 m a. s. l.) type locality of Trechisibus huascarani n. sp., as well as of Trechisibus recuayi n. sp. and Blennidus (Agraphoderus) huascarani Allegro, 2008.

FIGURES 13 – 16. Pronotum of Trechisibus: huascarani n. sp. HT (13); recuayi n. sp. HT (14); curtii n. sp. HT (15); lemairei n. sp. HT (16).