BELGRANDIELLA BOZIDARCURCICI N. SP., A NEW SPECIES FROM BOSNIA AND HERZEGOVINA (GASTROPODA: HYDROBIIDAE)

A new hydrobiid snail, Belgrandiella bozidarcurcici n. sp., is described from the rheocrene and rheopsammocrene springs situated in the canyon of the Cvrcka River, a region of Banja Luka, Republic of Srpska, Bosnia and Herzegovina. The concept of the genus Belgrandiella seems to be extremely artificial, but for the time being we keep the new species as a member of the genus based mainly on the shape of the shell of its type species, B. kusceri (Wagner, 1914).


INTRODUCTION
Species of the hydrobiid genus Belgrandiella are distributed from Austria (Glöer, 2002) to Bulgaria (Radoman, 1983;Georgiev, 2011).Records of species of this genus from Turkey, Ukraine, Caucasus and Lebanon (Schütt and Şeşen, 1993) are questionable and need further confirmation.Many species originally described in the genus Belgrandiella have later on been shifted to other genera (e.g., Boeters, 1999).
Most of species of the genus have a restricted distribution as dwellers of springs and subterranean waters.Haase (1994) showed an unusual lack of variability within each population of Austrian Belgrandiella.This was explained as a consequence of the presumed mode of dispersal of these crenobiontic snails, i.e. aerial transport with insects (Haase, 1994).
The distribution of the genus Belgrandiella in the Balkans shows a large gap between Bosnia and Herzegovina and Bulgaria (Fig. 1A).To date, only two species of the genus Belgrandiella, B. koprivnensis Radoman, 1975 andB. dabriana Radoman, 1975, have previously been described from Bosnia and Herzegovina (Radoman, 1983).
Fieldwork by Dejan Dmitrović (Banjaluka) in the region of the Cvrcka River canyon resulted in the discovery of one species new to science that will be presented in this paper.

MATERIALS AND METHODS
The benthic assemblages were studied from 50 spring habitats situated in the 17-km long canyon of the Cvrcka River, region of Banja Luka, Republic of Srpska (Fig. 2B).The samples were collected using a Surber sampler; freshwater snails were sorted in the laboratory with the aid of a stereo microscope and fixed in 70% ethanol.
Unless otherwise stated, the material was collected by Dejan Dmitrović (Banjaluka).Dissections and measurements of the genital organs and the shells were carried out using a stereo microscope, and photographs were made with a Leica digital camera system.The type material is stored in the Zoological Museum of Hamburg (ZMH).
(Fig. 2) Description -The elongated-oval shell is thickwalled and consists of 4-4.5 convex whorls with a small rounded apex and smooth surface.The shell is whitish translucent.The aperture is oval and in most specimens with a blunt angle at the top and a thickened peristome.The umbilicus is closed.The operculum is orange.Shell height 1.65-2.10mm (1.725, σ = ± 0.26), shell width = 0.9-1.2mm.
The mantle is dark with a white border at the head.The head and foot are white, the head with dark patterns at the forehead.Dark eyespots are visible.The penis is long and slim, acute at the tip, and without outgrowths.

Differential diagnosis -
The new species most closely resembles Belgrandiella kuesteri (Boeters, 1970).The latter species differs in having a more elongated shell and narrower egg-shaped aperture, which is rounded at the top.In addition, it has a strongly sinuated margin of the aperture.Radoman, 1975, known from Croatia and Bosnia and Herzegovina, can be distinguished from B. bozidarcurcici n. sp. by proportionally shorter shells, rather thin aperture margins with the columellar one being applied to the shell wall, often reduced to a callus (Radoman, 1983).B. dabriana Radoman, 1975, known only from the spring of the Dabar River (S of Sanski Most) differs from the new species in having a slit-like umbilicus and a rather low and wide aperture (Radoman, 1983)  Distribution -Bosnia and Herzegovina, canyon of the Cvrcka River.

Belgrandiella koprivnensis
Habitat and ecology -In the study area, this species was found to be common in rheocrene and rheopsammocrene springs in deciduous forests dominated by common beech (Fagus sylvatica L.); only a few specimens were taken from the springs.The species was collected within an altitudinal range of 372 to 808 m, and possibly its vertical distribution ranges from the uppermost edge of the oak belt, and comprises the beech belt up to its higher parts.In some springs, Belgrandiella bozidarcurcici n. sp.lives together with Bythinella schmidtii, Radix labiata and Galba truncatula.

DISCUSSION
Species of the genus Belgrandiella are characterized by an oval to elongated-oval shell with a pointed apex, whorls rapidly increasing with a prominent body whorl and a nearly horizontal suture.The aperture is oval and angled at the top, at the columella lip-like thickened (Boeters, 1998).Belgrandiella is widely distributed from Austria to the Caucasus and Lebanon (Schütt and Şeşen, 1993).However, without question this concept of the genus Belgrandiella seems to be extremely artificial.The type species Belgrandiella kusceri (Wagner, 1928) has a strongly sinuated margin of the aperture and the penis has a "characteristic backward-turned, hook-shaped outgrowth" (Radoman, 1983).Other Belgrandiella species, e.g. the Austrian species, have a broad triangular penis (Haase, 1994(Haase, , 1996) ) and those from Bulgaria have a simple penis without any outgrowth, blunt at the penis tip (Glöer and Georgiev, 2009).Schütt and Şeşen (1993) did not provide anatomical data for the species from Turkey, Ukraine, the Caucasus and Lebanon assigned to the genus Belgrandiella.It is likely that the genus Belgrandiella is polymorphic or a complex of sibling genera with possibly limited distributions.However, resolving this problem is not possible without the application of molecular techniques.