New subterranean freshwater Molluscs from Bosnia & Hercegovina ( Mollusca : Hydrobiidae )

Recently collected materials from Bosnia & Hercegovina revealed 5 new species of the genus Bythiospeum: B. blihensis n. sp., B. hrustovoensis n. sp., B. maroskoi n. sp., B. plivensis n. sp., and B. petroedei n. sp. In addition a new Islamia could be found, described here as I. steffeki n. sp. Photos of holotypes and paratypes are presented in addition to descriptions.

Islamia is a genus, widely distributed in the Balkans from Bosnia to the Near East and also in France, Spain and Italy (Bodon et al. 2001) and the species of which occur in underground water and springs.
Of both genera mentioned above the species predominantly have been described by the shells only, because the subterranean living specimens do not reach the surface and only empty shells can be found.
Recently, the junior author collected in springs in Bosnia & Hercegovina new hydrobiid snails which we describe here as new.Descriptions and photos of these species are presented in this paper.

Material and Methods
The snails were collected by the junior author from sand samples of the fraction 0.3-3 mm, fixed with alcohol and then wet screened under binocular microscope .The wet sand sample was consequently dried, and extracted the rest of the dry shells.
The dissections and measurements of the genital organs and the shells were carried out using a stereo microscope; the photographs were made with a digital camera system (Leica R8).
We work with an indirect species concept of which every species has at least one constant feature that allows us to distinguish it from other species.A constant distinguishing feature shows that speciation has taken place.In addition zoogeographical aspects should be also taken into consideration (see Glöer et al. 2010).
The used terms to describe the shells follow Hershler & Ponder (1999).The material is stored in the Hungarian Natural History Museum (HNHM), Budapest and in the private collections of the authors.
Locus typicus: Bosnia & Hercegovina, Bosnian Federation, Bihać district, Donji Kamengrad, about 1 km S of crossing from road R405 direction below quarry, about 250 m from last houses at S side of the village.Spring at left side of old dry canyon of Bliha (situated about 1 km south from the active canyon), a small spring among bushes and vegetation with small rocky cascades reaching the meadow.On the meadow at valley bottom is a small rock ring supported well where had been detected the same species.Sandy sediment from spring zone (1) and from well (2): N44.779470°, E16.566431° (spring) and N44.779547°, E16.566860° (well); Jozef and Maroš Grego leg., 04.04.2015.
Etymology: Named after rivulet Bliha which formed the dry canyon with the type locality and recently draining the active canyon about 1km north.

Description
Shell.The whitish and silky shell is elongate-conic with 5.5-6 convex whorls separated by a deep sutur, apex blunt.The umbilicus is slit-like, aperture oval, slightly sinuated outer lip from lateral view.Shell height 2.9-3.1 mm, width 1.3 mm.
Differentiating features: Bythiospeum blihensis n. sp. is the largest species of the here described species, only B. plivensis n. sp. is similar in size but B. plivensis n. sp. has a very large aperture.
Locus typicus: Bosnian Fedeartion, Bihać district, Hrustovo, 1.5 km E of village, at bottom of valley below entrance of cave Hrustovačka pećina-spring 1 under dense vegetation coming from large debriss with sand deposits at bottom of spring zone and at side of spring rivulet; N44.674682°, E16.700246°; 04.05.2015Jozef and Maroš Grego leg.
Remark: Between spring 1 (closest to cave entrance) and spring No. 3 150 m E of spring 1 is a spring No. 2 with cleaned out sediments, weak flow rate and stagnant water in a flooded cave entrance during our visit.The species had been found only in spring 1 and 3 so far (Figs. 1, 6).
Etymology: Named after village of Hrustovo in which vicinity the locus typicus is located.Etymology: Named after Maroš (Maroško) Grego, young enthusiastic documentarist of the Balkans, son of junior author, who helped to collect the species within the field trip.

Description
Shell.The whitish and silky shell is elongate-conic with 5.5 convex whorls and deep suture, apex blunt.The umbilicus is slit-like, aperture nearly oval, slightly sinuated outer lip from lateral view.Shell height 2.3-2.5 mm, width 1.0-1.1 mm.
Anatomy.The penis is triangular, distally pointed.

Description
Shell.The whitish and silky shell is elongate-conic with 5.5 regular growing convex whorls with a deep suture, apex blunt.The umbilicus is closed, aperture nearly circular and large, slightly sinuated outer lip from lateral view.Shell height 2.7-2.8mm, width 1.3-1.5 mm.
Differentiating features: Bythiospeum petroedei n. sp.differs from B. maroskoi n. sp. in size.From B. blihensis n. sp. it differs in the aperture, which is in B. plivensis n. sp.larger.

Description
Shell.The whitish and silky shell is elongate-conic with 5.5 whorls, apex blunt.The umbilicus is closed, aperture oval, slightly sinuated outer lip from lateral view.Shell height 2.0-2.3 mm, width 1.0-1.1 mm.
Etymology: The species is named after the ever helpful and untimely deceased prof.Jozef Šteffek, a dedicated malacologist of Banská Štiavnica, Slovakia.

Description
Shell.The whitish shell is conical with 5.5 fast growing convex whorls separated by a deep suture.The aperture is circular, the umbilicus as wide as the half of the penultimate whorl.Shell height 1.6-1.7 mm, width 1.7-1.9mm.Operculum light orange, concave without a peg.Differentiating features: The spire is higher and the whorls are more convex than all Islamia spp.mentioned by Radoman (1983) and Bodon et al. (2001).
Distribution: Known from type locality and sampling site 3 at Gornja Pećka and Izvor Plive 1A and 1B.

Discussion
The shells of the genus Iglica Wagner, 1927 look similar to Bythiospeum, but the outer lip of the aperture is straight and not sinuated, therefor we assigned the new species to the genus Bythiospeum.In addition the shells of the new species look similar to Bosnidilhia Boeters, Glöer & Pešić, 2013 but the shells of which are smaller and cylindrical and not elongated conical.
The species seem to be locally endemic as it is in other countries.Interestingly on sampling site Izvor Plive two obviously distinct species occur (B.plivensis n. sp. and B. petroedei n. sp.) in relatively close springs.
We assigned Islamia steffeki n. sp. to the genus Islamia because this genus is widely distributed in the Balkans.All other valvatiform hydrobiids are locally restricted (Bodon et al. 2001).In addition we could find an operculum of this species which has no peg and is similar to those of other Islamia spp.
Recent studies showed that the Hydrobiidae and Moitessieriidae are underexplored in Bosnia & Hercegovina and so many new species could be found in the last years (Boeters et al. 2013, Glöer & Pešić 2014a, 2014b) and ongoing research is needed.