Grossuana beroni, 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 : 131-133

Grossuana beroni n. sp. ( Figs. 2 , 3 , 6-8 )

https://zoobank.org/ urn:lsid:zoobank.org:act:F8C2DAFC-0535-4E8E-A891-6F9ECFFA88AC

Material studied:

Holotype: shell height 1.7 mm, width 1.2 mm, from type locality (ZMH 140789).

Paratypes: 43 specimens in ethanol ( ZMH 140790 ) , 5 specimens in coll. Glöer, 22 specimens in coll. Georgiev.

Additional localities: (1) Greece, Thassos Island, spring below Drakotrypa cave, Panagia village N40 44 06.3 E24 44 02.2, 124 m a.s.l. ( ZMH 140792 : 35 specimens, 6 specimens coll. Glöer) and (2) 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. ( ZMH 140791 : 5 specimens, 4 specimens in coll. Glöer) .

Type locality: Greece, Thassos Island, North Aegean, a spring (water source) south of Skala Potamia near the round road of the island, N40 41 01.1 E24 46 16.7, 115 m a.s.l. ( Fig. 1 ) .

Etymology: Named in honor of Prof. Petar Beron (National Natural History Museum - Sofia) who paid attention on this island and inspired D. Georgiev in its young age by his books.

Description: Shell: The corneous, small shell is ovate with a prominent body whorl. The 4-4.5 whorls are convex with a weak suture, with smooth surface and fine growth lines. The aperture is rounded ovate with a sharp periostome thickened at the columella. The umbilicus is closed ( Fig. 2 ). The operculum is dark red. Animal: The animal is mostly dirty whitish or gray colored. The mantle is white or gray with a black wide stripe in its middle. The snout and tentacles are whitish or gray. Small patches of black pigment are visible around eyes and at the base of the snout. Penis: The penis is nearly regularly broad with a long tapered penis-tip and a bilobed outgrowth in the middle part on the left side. There is a dark spot near the penis-tip.

Differentiating features: Grossuana beroni n. sp. is most similar to Grossuana marginata (Westerlund, 1881) from which it differs by more regularly growing whorls, sharper and thinner periostome and lighter soft body pigmentation. The new species is also similar to Grossuana sidironerensis Glöer, Reuselaars & Papavasileiou, 2018 described from the area of Drama at the mainland of Greece ( Glöer et al., 2018) but the last species has a penis with shorter tip, black colored mantle, and its whorls are fast growing (as in G. marginata ).

Distribution: Known only from few springs on Thassos Island: a spring (water source) south of Skala Potamia near the round road of the island (type locality), spring below Drakotrypa cave, Panagia village, and a big spring in the yard of the church of Rachoni village.

Habitat: Karst spring in a mixed broad leaf forest (mainly Platanus orientalis and Quercus spp. ). Found on moss, dry leaves, sand and stones.

Figures

Figure 1. Faksimile of the original description of Amnicola charpentieri Roth, 1855

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 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.

Figures 6-10. The Grossuana spp. 6-7: G. beroni n. sp. (paratypes), 8: penis of G. beroni n. sp. 9: G. thasia n. sp (holotype), 10: penis of G. thasia n. sp.