Two new and rare mountain door-snails (Gastropoda, Pulmonata, Clausiliidae) from high mountain areas in Macedonia

Abstract Two species of Clausiliidaeare described as new to science. Euxinella alpinella sp. n. is the fourth species within genus Euxinella Nordsieck, 1973, and Vestia lazarovii sp. n. is the second species of genus Vestia recorded from the Republic of Macedonia. In both species, the clausilium apparatus shows a high degree of variation.


Introduction
Until recently, only one species of the genus Euxinella with its locus typicus in the Bistra Mountains in Republic of Macedonia was known: Euxinella radikae radikae Nordsieck, 1973. Dedov andNeubert (2009) expanded the known distribution of the nominotypical subspecies to the Jablanitsa Mountains (Republic of Macedonia) and published a new subspecies, E. radikae hristovskii Dedov & Neubert, 2009 from the Gyonovitsa Cave, Bukovich Hill (Republic of Macedonia). They also described a new species E. subaii Dedov & Neubert, 2009, from the Mihailovo Mountain Resort in the Kozhuf Mountains (Republic of Macedonia). E. subaii shows some shell morphological characters that are not conform to the generic definition of Euxinella (Nordsieck, 1973) as for example a very long lamella subcolumellaris. It would be desirable to investigate the morphology of the genital system of all meanwhile known representatives of Euxinella in order to improve the generic diagnosis (cf. Dedov and Neubert 2009). E. alpinella sp. n. is the second species within the genus with a long subcolumellaris, and thus is probably close to E. subaii.
The genus Vestia was mentioned for the first time from the Republic of Macedonia by Urbanski (1960) from Osogovo Mountains, Kalin Kamen area, 1560 m a.s.l. with Vestia (Brabenecia) ranojevici ranojevici (Pavlovic 1912), which was later confirmed by H. Nordsieck (1974). Dedov (2010) added another record of this subspecies from a new site in the Osogovo Mountains (particularly from the Bulgarian part of the mountains).

Material and methods
Most of the material was collected by the author in 2009 and 2010 from the Nidzhe and Baba Mountains, Republic of Macedonia. The first specimens of Vestia lazarovii sp. n. were collected by Dr. Stoyan Lazarov in 2002, Baba Mountains. All the snails were hand-collected. The material is deposited in the private collection of the author (coll. DED.), in the National Museum of Natural History, Sofia (NMNHS), and in the Senckenberg Museum, Frankfurt am Main (SMF). The morphological examinations were carried out with a stereomicroscope.
Differential diagnosis. The new species differs from the two subspecies of Euxinella radikae -E. r. radikae and E. r. hristovskii -by occasional presence of a short basalis and the long subcolumellaris, which is visible from outside the aperture. E. alpinella sp. n. differs from E. subaii by its pale or missing palatal callus, the much shorter or missing basalis, and its shorter palatal plicaes.
Description of type series: shell small, spindle-shaped; shell colour brownish; suture deep; teleoconch striated, finely ribbed on the last whorls of the shell; neck with pronounced basal keel; aperture pear-shaped, in some specimens a slight palatal thickening present situated in parallel to its edge; well developed basal canal, often with a short basalis on its left margin; superior lamella connected with spiralis through a slight depression in the contact zone (or both situated very close, not connected); inferior lamella (columellaris) well developed running steeply nearby parietal side; lunella in dorsal position, sometimes reduced to a pale thickening or short straight plica; principal plica well developed; upper palatalis present, very short; subcolumellar lamella long and visible from outside the aperture, often forming part of the right margin of the basal canal; clausilium partly visible from outside the aperture, ovalorthogonal, distally with a weak edge.
Etymology. This species is named "alpinella" because of its isolated type locality in the alpine area.
Distribution. Euxinella alpinella sp. n. occurs in open alpine terrains on limestone, up to 2000 m a.s.l. Until now, the species is known only from its type locality, Nidzhe Mountains, in the southern part of the Republic of Macedonia.
Ecology. This species occurs on rocky alpine meadows above the timber line, on limestone rocks and in their crevices and under stones.
Comments. Euxinella alpinella sp. n. is now the fourth representative of the genus Euxinella. It shows shell morphological characters more similar to the forest species E. subaii, than to the petrophilous species E. radikae (trace of palatal callus, long subcolumellar lamella, basalis present). In E. radikae, the subcolumellaris ends at the level of the lunellar system, which this forms part of the definition of the genus (see also Dedov and Neubert 2009). However, E. alpinella sp. n. is the second species which shows differences in this character. As an "alpine form" (for this term cf. Nordsieck 2008), Euxinella alpinella sp. n. shows the highest shell morphological variation among all species of the genus Euxinella (different level of reduction of the clausilium aparatus -present or missing of basalis, upper palatal plicae and palatal callus; different intensity of development of lunella -pale thickening or short straight plicae; connected or separated lamella superior and spiralis). The morphological similarity between E. subaii and E. alpinella indicates some affinities between both taxa, and their particular distribution ranges, the Kozhuf and Nidzhe mountain, are quite close. Probably, both species originate from a parent taxon whose populations have been isolated ecologically (Euxinella subaii in deciduous forests, Euxinella alpinella sp. n. in alpine mountain meadows and on as well as under rocks). A similar distribution pattern of related species from the Kozhuf and Nidzhe Mountains can even be observed in more mobile organisms such as Tapinopterus heyrovskii Jedlicka, 1939 andTapinopterus purkynei Jedlicka, 1928 (Coleoptera: Carabidae), and Dorcadion heyrovskii Breuning, 1943 and Dorcadion purkynei Heirovsky, 1925 (Coleoptera: Cerambycidae) (Hristovski pers. comm.).

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Subcolumellaris ends at the level of the lunellar system. Palatal callus missing.
Description of type series. shell relatively small, spindle shaped, yellowbrownish coloured; whorls 8.5-9.5, including 2-2.5 smooth protoconch whorls; teleoconch ribbed (R = 38-54); aperture oval pear-shaped with a whitish, weekly reflected lip; a pale palatal callus present in some specimens; basal canal and keel missing; sinulus wide, not inclined to the shell axis; superior lamella connected with spiralis or close to it; inferior lamella turning widely-spirally; lunella and basalis missing; principal and upper palatal plica usually present; principal plica very short to about 1/3 of the last whorl; upper palatal plica short or missing; clausilium plate varying from hook-shaped in its end as is typical for Vestia, or with a weak hook and thin clausilium plate.
Etymology. This species is named after the Bulgarian arachnologist Dr. Stoyan Lazarov-Panagyrsky, B. A. S., Institute of Zoology, who was the first to collect this species.
Distribution. V. lazarovii sp. n. is currently only known from two sites at 1450 and 1650 m a.s.l. from the Pelister (= Baba) Mountains, Republic of Macedonia.
Ecology. This species occurs in the Pinus peuce forest ecotone, under logs of dead wood near Kopanke hut, as well as in the Pinus peuce forest ecotone in the Palisnopje area, under logs and fallen trunks.
Comments. The first species of genus Vestia to be reported from Macedonia (Urbanski 1960) was V. ranojevici. Nordsieck (1974) reported it from the Osogovo Mountains, Kalin Kamen area, 1560 m a.s.l., Kriva Palanka district, near to the border with Bulgaria. V. lazarovii sp. n. is the second representative of the genus from the Republic of Macedonia and occurs relatively high up in the mountains (in coniferous forests and its ecotone) and is characterized by a quite strong reduction of the clausilium apparatus (reduced lunella, short principal and short or missing upper palatal plicae, missing basalis, somethimes very fine and thin clausilium plate with weakly developed hook at its end). A connection between superior and spiral lamellae is typical for the  genus Vestia, so the specimens with disconnected superior and spiral lamellae could be also interpreted as showing initial reduction in this part of the clausilium apparatus.