Some new Bythinella spp. from southern Greece (Gastropoda: Bythinellidae)

In addition to a recent compilation of the Greek Bythinella spp. nine more species are described as new for science from Parnassus Mountains, Peloponnese Peninsula and Kithira Island. They are compared with the hitherto known species. For the protection of the mostly very small populations we only took a few specimens, not enough for dissections. Therefore, the descriptions are based on shell characters only which show a great diversity in Greece.

The measurements of the shells were carried out using a stereo microscope (Zeiss). The type material is stored in the Zoological Museum of Hamburg (ZMH), Germany, whilst some paratypes are deposited in the private collection of the co-author. The shell photos were made with a digital camera system (Leica R8).

Results
On Peloponnese Peninsula some Bythinella populations described by Reischütz et al. (2008) and Glöer & Reuselaars (2020) could be confirmed and additional springs were investigated. Four species turned out to be new to science and one species from Mari, recently figured by Reischütz et al. (2008), can be formally described. In Parnassus Mountains (Phocis) two new species were found. No Bythinella sp. has hitherto been described from Kithira Island. We found populations in the "Valley of the Mills" near Mylopotamos and in Amir Ali close to Karavas. They show different shell characters in comparison with the Peloponnese species.   Reischütz et al., 2008, 3: B. petrosensis Glöer & Reuselaars, 2020, 4: B. liandinaensis Glöer & Reuselaars, 2020, 5: B. beckmanni Reischütz et al., 2008 In summary, 29 Bythinella spp. are now known from Greece. One additional ssp. (B. charpentieri cabirius Reischütz, 1988)  Etymology: The new species is named after the Byzantine church Agia Eleousa. The type locality is situated just below that ruin.
Description: Shell: The shell is cylindrical with a flat apex and relatively broad. The 4.5-5 whorls are slightly convex with a clear suture. The body whorl takes about 0.75 of shell height. The aperture is ovate, with a sharp peristome. The umbilicus is slit-like. The shell is 2.8-3.1 mm high and 1.8-1.9 mm broad.
Differentiating characters: The new species exhibits the smallest length to width ratio (1.50-1.55) of all Greek Bythinella species. The most similar form is B. kwanti Glöer & Reuselaars, 2020, from the area of Kalavrita with a ratio of 1.6. In all other species that ratio is (much) higher.
Distribution: Only known from type locality on the northern slope of the Parnassus Mountains. Etymology: The new species is named after the type locality Kastalia Spring in Delphi.

Description:
Shell: The shell is ovate cylindrical with a small and flat apex. The 4.5-5 whorls are convex with a deep suture. The body whorl takes about 0.7 of shell height. The aperture is ovate and slightly angled at the top. The peristome is sharp, somewhat thickened at the columella. The umbilicus is closed. The shell is 2.5-2.8 mm high and 1.6-1.7 mm broad.
Differentiating characters: The length to width ratio of the new species (1.65) is between the higher and more slender B. charpentieri (Roth, 1855) , 1 subadult).
Etymology: The new species is named after the Taygetos Mountains.

Description:
Shell: The shell is elongated cylindrical. The 4.5-5 whorls are slightly convex with a clear suture. The body whorl takes about 0.7 of shell height. The aperture is ovate, angled at the top, with a sharp peristome which has a brown border. The umbilicus is closed. The shell is 2.4-2.9 mm high and 1.4-1.6 mm broad.
Etymology: The new species is named after the always corroded shell.

Description:
Shell: The shell is conical with the uppermost part of the embryonic whorl erected and detached. In some specimens two or more whorls are detached with a corkscrew-like appearance. The first whorls are more or less strongly corroded. The aperture is ovate, with a sharp peristome. The umbilicus is closed. The shell is 1.8-2.6 mm high and 1.3-1.5 mm broad and has about 3-3.5 whorls.
Differentiating characters: No other Greek species shows an erected apex and partly detached whorls. B. beckmanni with the same size is much more slender and cylindrical.
Distribution: Only known from type locality at the shore of Limni Moustou. Remarks: All specimens are strongly corroded and more or less deformed. Out of more than 30 investigated specimens no one showed a "normal" shape. The reason is unknown and could be due to parasitism or chemical influences. This species is the only one in Greece that lives at sea level.

Bythinella petrosensis Glöer & Reuselaars, 2020 [fig. 3.3]
Remarks: The sampling site was investigated again on 28.04.2019. Bythinella petrosensis was found for the first time in natural habitat few meters beside the artificial basin (type locality). The Bogreika Kalivia Spring consists of several sources that are scattered in a small valley in mountain forest. The species was found only in one tiny spring next to the main brook. The artificial basin was nearly dried out and no specimens could be found there in 2019.