Bythinella rachonica, Georgiev & Glöer, 2020

Georgiev, Dilian & Glöer, Peter, 2020, Three new hydrobiid species from Thassos Island (Greece) with a re-description of Amnicola charpentieri Roth, 1855, Ecologica Montenegrina 35, pp. 129-137 : 135-136

Bythinella rachonica n. sp. ( Figs. 2 , 22-25 )

https://zoobank.org/ urn:lsid:zoobank.org:act:DD058BE9-160A-4CA0-8ECB-7F5E642420DC

Materials studied:

Holotype: shell height 3.1 mm, width 1.75 mm, from type locality ( ZMH 140795 ).

Paratypes: 3 specimens in ethanol ( ZMH 140796 ) , 1 specimen in coll. Glöer.

Type locality: Greece, Thassos Island, North Aegean, a big spring in the yard of the church of Rachoni village , N40 45 29.6 E24 38 17.3, 107 m a.s.l. ( Fig. 4 ) .

Etymology: Named after village of Rachoni where the new species was found.

Description: Shell ivory, cylindrical with 4.5 whorls, separated by a deep suture. Surface silky and finely striated. Apex obtuse, umbilicus closed. Aperture oval, with a sharp peristome, angled at the top. Shell height 2.9-3.1 mm, width 1.8 mm. Penial appendix twice longer than the penis, tubular gland medium-sized, with 5 half loops, tapering from distal to proximal part ( Fig. 5 ).

Differentiating features: From this region no Bythinella spp. are known ( Glöer & Hirschfelder 2020, Glöer & Reuselaars 2020a, b, c), except from the neighbouring Samothrake Island, from where Reischütz described Bythinella charpentieri cabirius P.L. Reischütz 1988 (considered as a separate species by Glöer &

Georgiev 2012), which is a small and slim species (2.5-2.7 mm high and 1.2-1.3 mm broad) ( Glöer & Georgiev 2012) and in this way different from Bythinella rachonica n. sp.

Distribution: Known only from the type locality. The spring at the Agora of Limenas was checked but no living snails were found. Some empty, eroded shells of a Bythinella species were found by D. Georgiev in sand deposits in a spring below Panagia village (N40 43 56.8 E24 44 26.6, 49 m a.s.l.) but it is not clear if they belong to Bythinella rachonica n. sp.

Habitat: Found in a spring (captured under the church of Rachoni, with a concrete bed) on stones and submerged mosses.

Figures

Figure 2. The sampling sites of the species under discussion on Thassos. 1: Rachoni village: type locality of Bythinella rachonica n. sp., localiy of Grossuana beroni n. sp.; 2: Drakotrype cave, Panagia village: localiy of Grossuana beroni n. sp.; 3: type localiy of Grossuana beroni; 4: type locality of Grossuana thasia n. sp., 5: Pernes Mountain, type locality of Bythinella reischuetzi n. sp., 6: Hymettos, type locality of Bythinella charpentieri (Roth, 1855).

Figures 22-25. Bythinella rachonica n. sp., 22: shell, 23: penis in situ, 24: penis with penial appendix, 25: tubular gland.

Figures 3-5. 3: Type locality of Grossuana beroni n. sp., water source south of Skala Potamia near the round road of the island. 4: Type locality of Grossuana thasia n. sp., a spring south of Kinira near the round road of the island. 5: Type locality of Bythinella rachonica n. sp.