Euxinella alpinella, Dedov, Ivaylo Kanev, 2012

Dedov, Ivaylo Kanev, 2012, Two new and rare mountain door-snails (Gastropoda, Pulmonata, Clausiliidae) from high mountain areas in Macedonia, ZooKeys 168, pp. 45-53 : 45-48

Euxinella alpinella sp. n. Fig. 1

Locus typicus.

Republic of Macedonia, Nidzhe Mountains, Belo Grotlo peak, 40°59'17.9'N, 21°49'10.7'E, 2164 m a.s.l., limestone, under stones, 07. June 2010, leg. I. K. Dedov (43 specimens, collected alive, dried). Until now, the new species is known only from the type locality.

Type material.

holotype SMF 336340; paratypes: SMF 336341/2 specimens, NMNHS/ 2 specimens, DED/MK 635/38 specimens.

Differential diagnosis.

The new species differs from the two subspecies of Euxinella radikae - Euxinella radikae radikae and Euxinella radikae hristovskii - by occasional presence of a short basalis and the long subcolumellaris, which is visible from outside the aperture. Euxinella alpinella sp. n. differs from Euxinella 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, oval-orthogonal, 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. isnowthe fourth representative of the genus Euxinella . It shows shell morphological characters more similar to the forest species Euxinella subaii , than to the petrophilous species Euxinella radikae (trace of palatal callus, long subcolumellar lamella, basalis present). In Euxinella radikae , thesubcolumellaris 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, Euxinella 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 Euxinella subaii and Euxinella 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 and Tapinopterus purkynei Jedlicka, 1928 ( Coleoptera : Carabidae ), and Dorcadion heyrovskii Breuning, 1943and Dorcadion purkynei Heirovsky, 1925 ( Coleoptera : Cerambycidae ) (Hristovski pers. comm.).

Key for determination of the species and subspecies of the genus Euxinella .