Revision of ‘ Horatia’ snails (Mollusca: Gastropoda: Hydrobiidae sensu lato) from South Caucasus with description of two new genera Author Vinarski, Maxim V. Museum of Siberian Aquatic Molluscs, Omsk State Pedagogical University, Omsk, Russian Federation; Author Palatov, Dmitry M. Department of Hydrobiology, Biological Faculty, Moscow State University, Moscow, Russian Federation; Author Glöer, Peter Biodiversity Research Laboratory, Hetlingen, Germany text Journal of Natural History 2014 J. Nat. Hist. 2014-05-29 48 37 - 38 2237 2253 https://www.mendeley.com/catalogue/1fb8d12d-8ca7-3e1e-b45f-1432561ada37/ journal article 10.1080/00222933.2014.917210 1464-5262 5194243 4EDFB2AE-CB1D-4113-8CC7-3A1BBB46D838 Genus Motsametia gen. nov. Type species Horatia borutzkii Shadin, 1923 Diagnosis Shell very small (up to 1.5 mm in height), ovate-conical (valvatoid), with relatively large rounded aperture. Whorls (up to 3.5) convex, separated by a deep suture. Surface of protoconch is covered by small and densely situated honeycomb-like pits. Surface of teleoconch covered by rather rough growth lines. Umbilicus deep and narrow, funnel-like. Operculum unknown. Penis slender, elongated, slightly swollen in its middle part. Its lobe situated about 1/3 of the penis length is thin and slim tapered. Etymology The name is derived from the Motsameta (‘Martyrdom’) Monastery in Kutaisi ( Georgia ) located near the locus typicus of the single species of this genus. Gender – female. Figure 7. Shells of Motsametia and Pontohoratia . (A, B) Pontohoratia birsteini comb. nov. , Tsebeldinskaya Cave; (C) Pontohoratia birsteini comb. nov. , Niznheshakuranskaya Cave; (D) Pontohoratia smyri , holotype (Novoafonskaya Cave); (E) Motsametia borutzkii , topotype (Tskhal-Tsiteli Cave). Scale bars 300 μm. Figure 8. Habitats of Horatia -like snails in the caves of the South Caucasus. Left – Nizhneshakuranskaya Cave, right – Tskhal-Tsiteli Cave. Differential diagnosis Conchologically, snails of the genus Motsametia are similar to species belonging to the genera Horatia sensu Bodon et al. (2001) and Pontohoratia gen. nov. The differences between Motsametia and Horatia lie in the form and proportions of a penial lobe (short and obtuse in Horatia , thin and slim tapered in Motsametia ). The differences between Motsametia and Pontohoratia lie in different penis morphology (simple penis without penial lobes in Pontohoratia ; penis with a single penial lobe in Motsametia ). In addition, the aperture shape in Pontohoratia is angular, whereas in Motsametia it is almost regularly round. Distribution and species content The genus is endemic to South Caucasus (Transcaucasia) and includes the only species: M. borutzkii (Shadin) that is still known from its type locality only. The diagnostic characters of the species coincide with those of the genus. This is a rheophilic species found in underground brooks and springs. The stygobiont community of this cave was partially described by Birstein (1933) . Besides Motsametia , it includes several endemic species of crustaceans: Niphargus borutzkyi Birstein, 1933 (Niphargidae) , Troglocaris (Xiphocaridinella) kutaissiana (Sadovsky, 1930) (Atyidae) , and Asellus monticola fontinalis Birstein, 1936 (Asellidae) . Table 4 provides a morphological comparison of the two genera described here with other taxa of stygobiont valvatiform hydrobiids living in the South European region. Table 4. Comparative morphological characteristics of certain stygobiont genera of valvati- form hydrobiids occurring in the southern part of Europe.