Trechus ( Trechus ) nezlobinskyi , a new high-altitude ground beetle species from the Republic of Macedonia ( Coleoptera : Carabidae : Trechinae )

Trechus (Trechus) nezlobinskyi sp. n. is described from a high-altitude area of Jablanica Mt. (southwest Republic of Macedonia). The new species belongs to the “obtusiusculus” group of species and it is treated as most closely related to Trechus (Trechus) ravasinianus Lorenz, 1998 from Central Albania. The diagnostic characters of the new species are described and illustrated.


Introduction
The nominotypical subgenus of genus Trechus Clairville, 1806 counts over 850 species worldwide (Avone 2014), with cca.80 taxa (66 species) known from the Balkan Peninsula arranged in several species groups (Moravec et al. 2003;Lebenbauer 2004;Ollivier et al. 2008;Guéorguiev and Hristovski 2010).The most numerous species complex on the Balkans is the "obtusiusculus" group with more than 35 species distributed in South Europe and Lebanon.The species of the "obtusiusculus" group prefer limestone areas and highaltitude regions.Their body features (absence of wings, presence of small eyes, depigmentation) and ecological preferences (active at constant humidity and lower temperatures, low food requirements) led to geographic isolation and speciation on the high Balkan mountains (Jeannel 1927;Guéorguiev and Hristovski 2010).Hristovski et al. (2010) reported two Trechus (s.str.) taxa for Jablanica Mt. (south-west Macedonia): Trechus quadristriatus (Schrank, 1781) and Trechus (Trechus) sp.The re-examination of the male specimen of the latter taxon in 2012 revealed that it belongs to a new species for science from the "obtusiusculus" species group.In June 2013 five more specimens (4♂ and 1♀) were collected which enabled me the description of the new Trechus species from the Republic of Macedonia.

Material and Methods
The genitalia were extracted from two male specimens and then put consecutively in 10 % solution of potassium hydroxide, acetic acid and glycerin.The genital structures were glued on cardboards, which were pinned under the specimen from which they were extracted.

Research Article
The photographs of the male genitalia were taken with Nikon Coolpix 4500 camera attached to Nikon Eclipse E800 microscope.The corporal measurements of the specimens were done with a LOMO MBS10 binocular stereomicroscope by the aid of ocular micrometer with accuracy of 0.02 mm.The drawing of the copulatory piece was performed with Genius Graphic Tablet over the series of original photographs taken at different foci and different angles.

Species group "obtusiusculus"
The "obtusiusculus" species group of Trechus (s.str.)counts more than 35 species.Taxa from this complex populate France, Austria, Italy, the Balkan Peninsula and Lebanon, but in fact the most species occur both in Italy and the Balkan Peninsula (Casale & Laneyrie 1982;Moravec 1986;Vigna Taglianti 1994;Moravec et al. 2003).
All of the specimens of the type series are kept in the collection of the Macedonian Museum of Natural History, Skopje, Republic of Macedonia.

Diagnosis
Trechus (Trechus) nezlobinskyi sp.n. can be easily distinguished from all the other species of the "obtusiusculus" group by the specific forms of the median lobe of the aedeagus and copulatory piece (Figs. 2  and 3).Most of the species of the "obtusiusculus" group have hooked apex of the median lobe, a characteristic not shared only by a few species (Trechus ravasinianus Lorenz, 1998, T. winkleri Jeannel, 1927 and T. nezlobinskyi sp. n.).Geographically, the closest representative of the "obtusiusculus" group to the new taxon is Trechus galicicaensis Guéorguiev & Hristovski, 2010, which has clearly hooked apex of the median lobe (Guéorguiev and Hristovski 2010: 75).
However, in a phyletic point of view, the closest relative to the new species is T. ravasinianus Lorenz, 1998 (syn: T. ravasinii Jeannel, 1927).The two species share similar external morphology and shape of the aedeagus, and they live in close geographic areas (Jablanica Mt. in SW Macedonia and Tomor Mt. in central Albania).The median lobe of both species is long and slender, the one of T. nezlobinskyi n. sp. has shorter apex with weaker upward incurvation, sub-apically more thickened (vs.less thickened in T. ravasinianus), with a rounded basal bulb (vs.somewhat elongate in T. ravasinianus) (Jeannel 1927) (Fig. 2).The copulatory pieces of the two species are evidently different; the one of T. nezlobinskyi sp.n. is shorter and has characteristic tongue-like structure (Fig. 3) while T. ravasinianus has semi-cylindrical and elongated copulatory piece with truncated end (Jeannel, 1927).
Trechus nezlobinskyi sp.n. differs from T. winkleri Jeannel, 1927 by the shorter bulb and longer apical part of the median lobe, different shape of the copulatory piece, and number of well-expressed elytral striae.The copulatory piece in T. winkleri is divided into two lobes, the ventral one is oval with longitudinal ridge, and the dorsal lobe is elongated and prolonged into apical apophysis (Jeannel, 1927) while the copulatory piece of Trechus nezlobinskyi sp.n. is shorter and more quadratic with tongue-like structure (much shorter than the apophysis in T. winkleri) (Fig. 3).Trechus nezlobinskyi sp.n. has striae 1-6 easily discernible on each elytron (Fig. 1), while T. winkleri has only striae 1-3 well noticeable on each elytron (Jeannel 1927).

Description
The description of Trechus nezlobinskyi sp.n. is based on morphological characteristics of the specimens from the entire type series (Table 1).Body elongated, slightly convex, apterous.Head, antennae, mouthparts, pronotum and elytrae brown (reddish-brown in teneral individuals), head darker than the rest of the body (Fig. 1), legs brown.Total body length 3.40-3.71mm (mean 3.57 mm) (Table 1).Microsculpture similar in both males and the female.Microsculpture of head fine, well visible, consisting of more-less isodiametric meshes; pronotum with hardly visible microsculpture at magnification x160; elytra with fine, but distinct transversal meshes.
Pronotum sub-cordate, wider than long (PW/PL ratio = 1.35), widest at the anterior third, the basal and apical margins equally long; the base rectilinear in the middle, slightly oblique towards hind angles; sides curved and convergent, strongly curved towards apical angles, less curved towards the hind angles, lateral margins rounded and convergent, strongly curved towards the fore angles, less curved towards the hind angles, very slightly concave immediately in front of the hind angles; hind angles obtuse, but almost rectangular, possessing a small denticle each (Fig. 1).Median furrow deep, extending to the basal margin of the pronotum; basal foveae distinct.Lateral margins flattened on their whole length.Pronotal disc smooth; surface near the hind angles consists of a distinct microsculpture of isodiametric meshes.
The first two articles of the male protarsi strongly dilated, the first article wider than the second one and more than twice as wide as articles 3-5 each.Female protarsi simple.Protibiae without longitudinal furrows on the external surfaces.
Median lobe of the aedeagus relatively long and slender, forming an obtuse angle with the basal bulb, sub-apically thickened in lateral view (Fig. 2a).The basal bulb small, rounded, more than three times shorter than the median lobe.Apical part of the median lobe ends in a long tip that is curved upwards (Figs.2a and 2b).The median lobe in dorsal view bowed to the left, the extended tip of the apical part pointing to the right (Fig. 2c).Parameres long, with a wide base each, narrowing towards the apices, each with a basal processus, bearing 3-5 distal setae each (Figs.2a and 2b).The copulatory piece relatively small, represented by a four-sided chitinized lamella placed longitudinally and vertically to the median lobe axis (lateral view), the proximal dorsal corner extended into a tongue, which is curved horizontally (Figs.3a and 3b).
Chaetotaxy: Similar to the other Trechus species of the "obtusiusculus" group.Labrum with six equidistant setae on the anterior margin; clypeus with four setae; frons with two pairs of supra-orbital setae.Pronotum with a pair of lateral setae at the anterior third and a pair of baso-lateral setae.Elytra with two parascutellar setae.Each elytron with two pairs of moderately deep setigerours punctures in third striae (the first one situated in anterior fourth of the elytron, while the second one situated in the middle of the elytron); umbilical series represented by four equidistant humeral setae, two median and two apical setae on each elytron (Fig. 1).

Table 1 .
Dimensions (mm)and ratios of the type specimens of Trechus (Trechus) nezlobinskyi sp.n.Abbreviations are explained in the Materials and methods chapter.