ZOOSYSTEMATICA ROSSICA I S S N Zoological Institute, Russian Academy of Sciences, St Petersburg ▪ https://www.zin.ru/journals/zsr/ 2410-0226 [online] Vol. 29(2): 258–266 ▪ Published online 11 November 2020 ▪ DOI 10.31610/zsr/2020.29.2.258 0320-9180 [print] RESEARCH ARTICLE Revealing the stygobiont and crenobiont Mollusca biodiversity hotspot in Caucasus: Part II. Sitnikovia gen. nov., a new genus of stygobiont microsnails (Gastropoda: Hydrobiidae) from Georgia Выявление центров биоразнообразия стигобионтных и кренобионтных моллюсков на территории Кавказа: Часть II. Sitnikovia gen. nov. – новый род стигобионтных микрогастропод (Gastropoda: Hydrobiidae) из Грузии E.M. Chertoprud*, D.M. Palatov & M.V. Vinarski Е.М. Чертопруд*, Д.М. Палатов, М.В. Винарский Elizaveta M. Chertoprud, Lomonosov Moscow State University, 1 Leninskie gory, Moscow 119991, Russia. E-mail: [email protected] Dmitry M. Palatov, Lomonosov Moscow State University, 1, Leninskie gory, Moscow 119991, Russia; A.N. Severtzov Institute of Ecology and Evolution, 33, Leninsky prospect, Moscow 117071, Russia. E-mail: [email protected] Maxim V. Vinarski, St. Petersburg State University, 7/9 Universitetskaya Emb., Saint Petersburg 199034, Russia. E-mail: [email protected] Abstract. A new genus of stygobiont hydrobiid snails, endemic to Georgia, is described. Sitnikovia gen. nov. includes two species: S. megruli sp. nov. and S. ratschuli sp. nov., known only from their type local- ities (Garakha and Sakishore caves). The data of shell characters, penial morphology, and radula of the new genus are provided. Резюме. Описан новый род эндемичных для Грузии стигобионтных моллюсков-гидробиид. Sitnikovia gen. nov. объединяет два вида, S. megruli sp. nov. и S. ratschuli sp. nov., – известных толь - ко из типовых местообитаний (пещеры Гараха и Сакишора). В работе приведены отличительные признаки раковин, радулы и анатомии мужской половой системы. Key words: aquatic malacofauna, stygobiont gastropods, taxonomy, Transcaucasia, Littorinimorpha, Hy- drobiidae, new genus, new species Ключевые слова: водная малакофауна, стигобионтные гастроподы, таксономия, Закавказье, Littorinimorpha, Hydrobiidae, новый род, новые виды ZooBank Article LSID: urn:lsid:zoobank.org:pub:E08FB2A0-AC73-418B-9732-FC73D80411A8 Introduction bogatov, 1962; Schütt & Şeşen, 1993; Grego et al., 2017). The recent works, including those based on Traditionally, the endemic species of the Cau- a molecular approach, have shown that most pro- casian hydrobiid snails were placed into genera bably all species of this family inhabiting Caucasus described from other territories, e.g. the Balkan and Transcaucasia must be classified within the Peninsula (Lindholm, 1913; Shadin, 1932; Staro- genera endemic to this territory (Vinarski et al., 2014; Glöer et al., 2015; Anistratenko et al., 2017; *Corresponding author Sitnikova et al., 2018; Vinarski & Palatov, 2019; © 2020 Zoological Institute RAS and the Author(s) E.M. Chertoprud et al. Sitnikovia, a new genus of snails from Georgia Grego et al., 2020). It seems that no Balkan hyd- collected from subterranean waterbodies situated robiid genera occur in the waters of Caucasus. To inside the caves. Living molluscs were hand-picked date, five endemic genera of the Caucasian hydro- from submerged stones and pebbles as well as from biids have been described: Shadinia Akramowski, the surface of rimstone pools. Empty shells were 1976, Motsametia Vinarski, Palatov et Glöer, 2014, sampled by means of a sieve with 0.2 mm mesh Pontohoratia Vinarski, Palatov et Glöer, 2014, from the sand. Sampled specimens were fixed with Nicolaia Glöer, Bößneck, Walther et Neiber, 2016, 90% ethanol. and Tschernomorica Vinarski et Palatov, 2019 (Vi- Digital images of 22 and 21 shells from the narski & Kantor, 2016; Vinarski & Palatov, 2019). Sakishore Cave and the Garakha Cave, respec- In this paper, a new genus and two new species tively, and the type specimens of the two new of stygobiont hydrobiids endemic to Georgia are species were made by a camera attached to Ste- described. The first part of this series was pub- reoscopic Microscope Micromed MC-5 ZOOM lished by Grego et al. (2020). LED. ImageJ 1.48v software (https://imagej. nih.gov/ij) was used for morphometric measure- Material and methods ments. Six standard measurements were taken from each specimen: shell height (SH) and width The material for the present study was col- (SW), aper ture height (AH) and width (AW), lected in two caves of Western Georgia (Saki- body whorl height (BWH) and width (BWW). shore and Garakha) and examined by us in 2017 The measurements were analysed by the principal and 2019. These caves belong to two geologically component analysis (PCA) using the PAST 2.0 and hydrologically isolated karstic areas, namely statistical software. the Odishi Plain (Samegrelo-Zemo Svaneti) and The scanning electron microscopy (SEM) ima- Shaori Lake hollow (Racha) (Fig. 1). Snails were ges of the shells were made in the Yu.A. Orlov at Fig. 1. Sitnikovia gen. nov. Type localities of S. megruli sp. nov. (1) and S. ratschuli sp. nov. (2). a – karst massif of Central Mengrelia approximately corresponding to the Odish Plateau, b – karst massif of Racha (after Tintilozov, 1976). ( Zoosystematica Rossica, Vol. 29, No. 2, pp. 258–266 259 E.M. Chertoprud et al. Sitnikovia, a new genus of snails from Georgia the Paleontological Museum of the Paleontolog- ical Institute of the Russian Academy of Scienc- es, Moscow, by means of Cam Scan S2 and Vega3 Tescan microscopes. The protoconchs and radulae were examined using a Cam Scan S2 SEM in the Electronic Microscopy laboratory of the Biologi- cal Faculty of the Moscow State University, Mos- cow. For counting of protoconch whorls and for measurements we followed techniques described by Anistratenko (2005). Among others, the di- ameter of the whole protoconch and the width of the initial non-spiral part of the embryonic shell (WE) were measured (Fig. 2). The holotypes and a part of the paratypes of the new taxa were deposited in the collection of the Zoological Institute of the Russian Acade- my of Sciences (ZIN), Saint Petersburg, Russia. Fig. 2. Sitnikovia megruli sp. nov. Schematic illustra- Other paratypes are kept in the Zoological Mu- tion of the initial non-spiral embryonic shell part width measurement (WE). seum of the Moscow State University (ZMMU), Moscow, Russia, and in the collections of the authors. The distal part of the penis is narrow and pointed; in its central part the penis is swollen; its width Taxonomic part slowly decreases towards the basal part. From all genera of the Caucasian hydrobiid Order Littorinimorpha Golikov & snails, established to the date, Sitnikovia gen. Starobogatov, 1975 nov. differs by a unique combination of general shell shape and the penis structure. Superfamily Truncatelloidea Gray, 1840 Etymology. Named after Dr. Tatiana Ya. Sitni- Family Hydrobiidae Stimpson, 1865 kova, a renowned Russian expert in systematics of Genus Sitnikovia gen. nov. the freshwater Caenogastopoda. Species composition. Sitnikovia gen. nov. in- Type species Sitnikovia megruli sp. nov. cludes two species described herein, both are en- Diagnosis. Shell high-conical, relatively slen- demic to Georgia. der (SW/SH ratio 0.40–0.60), with four to six slowly increasing whorls. Spire high, body whorl Sitnikovia megruli sp. nov. moderately inflated. Operculum ovate, corneous, (Figs 3a, 3c, 4a, 4c, 4e, 4g, 4i) thin and flat, without protrusions on the inner “Paladilhiopsis” sp.: Chertoprud et al., 2020: 275–289. side, paucispiral with submarginal nucleus, usu- ally orange or yellowish. Animal blind. Inner Holotype. Adult mollusc, Georgia, Samegrelo-Zemo Svaneti, Chkhorotsqu district, Odishi plain, left side callus not developed. Radula of taenioglossate of the Bulebe River, subterranean spring inside Ga- type, with formula 5-1-5-1-1; central (or rachidi- rakha Cave, 42°31′7.91″N 42°10′6.54″E, 207 m a.s.l., an) tooth with single pair of basal cusps. Lateral 03.II.2017, leg. D. Palatov, No. 514/1 (ZIN). tooth resembles rachis in its shape and position of Paratypes. 21 adult molluscs, same collecting data cusps, and bears eight or nine cusps (three or four as for the holotype, five under No. 514/2 (ZIN), three at inner side, one largest, four at outer side); inner under No. Lc-40753 (ZMMU) and the rest in collec- marginal tooth with 21–24 cusps, outer marginal tions of the authors. tooth with 16 cusps. Shell dimensions of the holotype (mm). WN Penis with a single dorso-lateral lobe, whose 4.75; SH 2.1; SW 1.15; BWH 1.15; BWW 1.0; AH appearance varies from a well-developed conical 0.75; AW 0.65. For morphometric characteristics offshoot to massive bulging with small knobby tip. of the entire type series see Table 1. 260 ( Zoosystematica Rossica, Vol. 29, No. 2, pp. 258–266 E.M. Chertoprud et al. Sitnikovia, a new genus of snails from Georgia Fig. 3. Sitnikovia megruli sp. nov. (a, c, e) and S. ratschuli sp. nov. (b, d, f). a, b – shell, holotype; c, d – penial morphology; e, f – type locality (e – Garakha Cave, f – Sakishore Cave). Scale bars: 0.5 mm (a, b); 0.2 mm (c, d). Table 1. Sitnikovia megruli sp. nov. and S. ratschuli sp. nov., conchometric characteristics of the type specimens. Species Character / index S. megruli (n = 21) S. ratschuli (n = 22) Whorl number 4.3–5.0 (4.7 ± 0.2) 4.0–5.1 (4.4 ± 0.3) Shell height, mm (SH) 1.7–2.2 (2.0 ± 0.1) 1.5–2.6 (1.9 ± 0.3) Shell width, mm (SW) 0.9–1.2 (1.0 ± 0.1) 0.9–1.4 (1.2 ± 0.3) Body whorl height, mm (BWH) 1.2–1.3 (1.2 ± 0.1) 1.0–1.7 (1.3 ± 0.1) Body whorl width, mm (BWW) 0.8–1.0 (0.9 ± 0.1) 0.9–1.2 (1.1 ± 0.2) Aperture height, mm (AH) 0.6–0.8 (0.7 ± 0.05) 0.6–1.0 (0.7 ± 0.1) Aperture width, mm (AW) 0.5–0.7 (0.6 ± 0.05) 0.5–0.9 (0.7 ± 0.1) SW/SH 0.45–0.57 (0.51 ± 0.03) 0.53–0.68 (0.60 ± 0.01) BWH/SH 0.59–0.69 (0.73 ± 0.02) 0.63–0.71 (0.67 ± 0.02) BWW/BWH 0.65–0.79 (0.73 ± 0.04) 0.71–0.94 (0.83 ± 0.01) AH/SH 0.30–0.38 (0.34 ± 0.02) 0.34–0.43 (0.38 ± 0.01) AW/AH 0.79–1.01 (0.90 ± 0.05) 0.82–0.98 (0.91 ± 0.04) ( Zoosystematica Rossica, Vol. 29, No. 2, pp. 258–266 261 E.M. Chertoprud et al. Sitnikovia, a new genus of snails from Georgia Fig. 4. Sitnikovia megruli sp. nov. (a, c, e, g, i) and S. ratschuli sp. nov. (b, d, f, h). a, b – shell, paratype; c, d – protoconch, lateral view; e, f – protoconch, apical view; g, h – radulae; i – operculum. Scale bars: 300 μm (a, b); 100 μm (c–i). 262 ( Zoosystematica Rossica, Vol. 29, No. 2, pp. 258–266 E.M. Chertoprud et al. Sitnikovia, a new genus of snails from Georgia Description. Shell small (SH < 2.25 mm), narrow, whereas in S. ratschuli sp. nov. it is rather high conical, relatively narrow and slender (SW/ shorter and swollen. There are no noticeable dif- SH ratio 0.45–0.60), whitish. Whorl number ferences in radular morphology between S. megru- up to 5.00. Whorls rounded and visibly convex, li sp. nov. and S. ratschuli sp. nov. separated by deep oblique suture. Spire high, its Etymology. Named after Samegrelo (Georgian height 0.60 SH or more. Body whorl high and სამეგრელო), a historic province in the western moderately inflated, its width slightly exceeds part of Georgia. width of penultimate one. Tangent line slightly Distribution. Endemic to Western Georgia. convex. Aperture ovate, with obtuse angle in its Known only from the type locality. upper part, more or less detached from body whorl Habitats and ecology. Inhabits a subterrane- wall forming a rather wide umbilicus. Shell sur- an spring in Garakha Cave (Fig. 3e), prevailing face almost smooth, with rare growth lines. Pro- on solid substrates. The densest aggregations of toconch broad, low domed, consists of 1.5 whorls snails were found in the small left tributary of the (330 μm in diameter, WE 220 μm). Surface of main cave stream. Molluscs were collected from protoconch covered by mesh-like microsculpture the submerged stones and from the surface of rim- with cellular pits of variable density. Pits of irreg- stone pools. Water indicators: T 11 °C, pH 8.5, to- ular shape, evenly immersed in protoconch sur- tal dissolved solids (TDS) 130 ppm. face. Protoconch separated from te leoconch by distinct and thin axial line. Operculum (Fig. 4i) Sitnikovia ratschuli sp. nov. ovate, corneous, thin, flat, without protrusions on (Figs 3b, 3d, 4b, 4d, 4f, 4h) inner side, paucispiral with submarginal nucleus, Holotype. Adult mollusc, Georgia, Racha-Lech- generally orange or yellowish. khumi, vicinity of Kveda Tlughi Village, Shaori Lake Radula (Fig. 4g). Two basal cusps on each side basin, subterranean river inside Sakishore Cave, of rachis and five cusps on each side of median 42°26′31.1″N 43°09′30.9″E, 1188 m a.s.l., 13.VIII. cusp of rachis. Median cusp only slightly longer 2019, E. Chertoprud leg., No. 513/1 (ZIN). than adjacent ones, all cusps relatively long and Paratypes. 22 adult molluscs, same collecting data narrow. On lateral tooth, there are four-five cusps as for the holotype, three under No. 513/2 (ZIN), three on each side of largest cusp (formula: (5)4-1-4), all under No. Lc-40754 (ZMMU) and the rest in collec- cusps long and narrow like those of rachis. Inner tions of the authors. marginal tooth with 21–24 cusps, outer marginal Shell dimensions of the holotype (mm). WN tooth with 16 cusps. 4.9; SH 2.15; SW 1.2; BWH 1.35; BWW 1.05; Penis (Fig. 3c) with well-developed dorso-lat- AH 0.8; AW 0.75. For morphometric characteris- eral lobe looking as short, conical, obtusely termi- tics of the entire type series see Table 1. nated process. Distal pointed part of penis very Description. Shell small (SH < 2.6 mm), high short and wide. conical, relatively slender (SW/SH ratio 0.56– Animal blind. 0.68), whitish. Whorl number up to 5.10. Spire Differential diagnosis. This species is similar to high, its height 0.46 SH or more, and can reach S. ratschuli sp. nov., except for being smaller (SH 0.9 mm. Body whorl high and rather convex, its does not exceed 2.2 mm) and having a rela tively width extends beyond width of penultimate one. narrower shell (SW/SH ratio 0.45–0.57). Body Tangent-line slightly concave. Surface of teleo- whorl is smaller and moderately inflated. Shell conch with rare growth lines. Whorls rounded proportions are noticeably slenderer. Aperture is and visibly convex, separated by deep oblique relatively small with similar proportions. The pro- suture. Aperture ovate, with obtuse upper angle. toconch of S. megruli sp. nov. is noticeably bigger Umbilicus well developed. Protoconch consists than that of S. ratschuli sp. nov. (Figs 4e, 4f). Sur- of 1.5 whorls (270 μm in diameter, WE 158 μm). face of protoconch has a similar mesh-like sculp- Surface of protoconch with mesh-like microsculp- ture, although its pattern is slightly different: pits ture. Protoconch separated from teleoconch by are irregularly shaped and equally impressed. The distinct axi al line. Operculum ovate, corneous, penial lobe in S. megruli sp. nov. is elongated and thin and flat. ( Zoosystematica Rossica, Vol. 29, No. 2, pp. 258–266 263 E.M. Chertoprud et al. Sitnikovia, a new genus of snails from Georgia Fig. 5. Sitnikovia gen. nov. Principal component analysis of whorl numbers and shell measurements (see Table 1 for data). Green circles – S. ratschuli sp. nov., red squares – S. megruli sp. nov. Three first principal components (PC) combined account for 97.3% of variance (PC1 70.4%, PC2 24.2%, PC3 2.7%). Radula (Fig. 4h). Central (rachidian) tooth has Inner marginal tooth with 24 cusps, outer mar- a pair of basal cusps, large median cusp and five ginal tooth with 16 cusps. lateral cusp on each side of it. Lateral tooth asym- Penis (Fig. 3d) massive and swollen in cen- metric, with eight cusps, three at inner side, one tral part, with bulging dorso-lateral lobe slightly largest, four at outer side (formula: 4-1-3). Median spaced from penis, and having miniature pointed cusp elongated, almost twice as long as adjacent tip. Distal part of penis abruptly tapers and forms ones, and overlaps adjacent inner marginal tooth. short, hook-shaped tip, curved downwards. 264 ( Zoosystematica Rossica, Vol. 29, No. 2, pp. 258–266 E.M. Chertoprud et al. Sitnikovia, a new genus of snails from Georgia Animal blind. so apparent, but the PCA analysis has shown that Differential diagnosis. This species is similar to S. megruli sp. nov. and S. ratschuli sp. nov. are S. megruli sp. nov., but is larger (SH up to 2.6 mm) more or less distinct: the “clouds” of points, cor- and having a relatively wider shell (SW/SH ratio responding to the two taxa, overlap only slight- 0.56–0.64). Body whorl is higher and more in- ly (Fig. 5). However, we are unable to report any flated, noticeably wider than the preceding one. shell measurement or ratio allowing one to dis- Aperture of similar proportions but larger. The tinguish the shells of the two species. The values protoconch of S. ratschuli sp. nov. is noticeably of all morphological indices of S. megruli sp. nov. smaller than that of S. megruli sp. nov. (Figs 4e, and S. ratschuli sp. nov. overlap (see Table 1). 4f). Surface of protoconch has a similar mesh-like However, the anatomical differences between sculpture although the pattern is slightly differ- the two studied forms alongside with a spatial iso- ent with irregular axial elevations forming feebly lation allow us to affirm their species distinctness. defined ridges surrounding the depressions. The The habitats of S. megruli sp. nov. and S. ratschuli penial lobe in S. ratschuli sp. nov. is low and wide, sp. nov. are located in two different speleoregions, whereas in S. megruli sp. nov. it is rather slender which are not interconnected either spatially or and pointed. There are no noticeable differences geologically. Samegrelo Odishi cave region is a in radular morphology between S. megruli sp. nov. cluster karst massif with a predominance of the and S. ratschuli sp. nov. Neogene age conglomerates, while the Racha cave Etymology. The name is derived from Racha region is located on the highlands and is com- (Georgian რაჭა), a historical highland region of posed of Upper Cretaceous limestone (Tintilozov, Western Georgia, located in the upper Rioni River 1976). Thus, two anatomically similar species are and at the foothills of the Greater Caucasus Range. distributed in currently isolated karst areas. The Distribution. Endemic to Western Georgia. disjunction of their ranges was probably formed Known only from the type locality. relatively recently, as a consequence of a marine Habitats and ecology. Inhabits subterranean transgression caused the flooding of the Colchis river flowing in the Sakishore Cave (Fig. 3f). Mol- Lowland. A molecular phylogenetic study is re- luscs live on the massive stones immersed in water. quired to test this hypothesis. S. ratschuli sp. nov. may be characterized as a rhe- Moreover, the Racha region, specifically the ophilic species that prefers submerged hard sub- Shaori karst plateau, is elevated by more than strates. Molluscs prevail in a truly underground 1000 m a.s.l., while most of the previously investi- part of a watercourse, whereas in the part of the gated caves are located at lower altitudes (e.g. Ga- cave where the sunlight penetrates only empty rakha Cave lies at 207 m a.s.l.). Thus S. ratschuli shells were found. sp. nov., a mountain species, has the most elevated habitat among other stygobiontic gastropods that Discussion have already been described. Due to the isolated The two new species, united here under the ge- location of the Shaori karst region, it is rather poor- neric name Sitnikovia gen. nov., are characterized ly studied in terms of the subterranean biology. by the similar features of penial anatomy, specifi- cally by the presence of a dorso-lateral lobe. The Acknowledgements main anatomical difference between the two spe- The authors thank Roman A. Rakitov (Yu.A. Or- cies is the shape and proportions of this lobe. Sig- lov Paleontological Institute of Russian Academy of nificant differences were found in the dimension- Sciences, Moscow) for help with obtaining SEM mi- al characteristics of the protoconch. Compared crographs and Rostislav R. Borisov (Institute of Fish- to S. ratschuli sp. nov., S. megruli sp. nov. has a eries and Oceanography, Moscow) for help in collect- noticeably larger embryonic shell which can be ing of the materials. The part of the SEM work was explained by the lecitotrophic type of embryonic performed at the User Facilities Centre of the M.V. Lo- development, when the nutrients for developing monosov Moscow State University, Moscow, under the embryos come from the large and yolk-rich oocyte. financial support of the Ministry of Education and Sci- The differences between the teleoconchs are not ence of Russian Federation. This study was partially ( Zoosystematica Rossica, Vol. 29, No. 2, pp. 258–266 265 E.M. Chertoprud et al. Sitnikovia, a new genus of snails from Georgia funded by the Russian Foundatio for Basic Research biidae) from Georgia with description of five new (project No. 19-04-00270). The authors express their genera and twenty-one new species. ZooKeys, 955: gratitude to the two referees, Vitaliy V. Anistratenko 1–77. https://doi.org/10.3897/zookeys.955.51983 and Peter Glöer, for their valuable comments on the in- Lindholm W.A. 1913. Beschreibung neuer Arten itial version of the manuscript. und Formen aus dem Kaukasus-Gebiete. Nach- richtsblatt der Deutschen Malakozoologischen Ge- sellschaft, 45: 17–23; 62–69. References Schütt H. & Şeşen R. 1993. Pseudamnicola species Anistratenko V. 2005. Morphology and taxonomy of and other freshwater gastropods (Mollusca, Gas- Late Badenian to Sarmatian Mohrensternia (Gas- tropoda) from East Anatolia (Turkey), the Ukraine tropoda: Rissooidea) of the Central Paratethys. and the Lebanon. Basteria, 57: 161–171. Acta Geologica Polonica, 55(4): 371–392. Shadin W.J. 1932. Die Süßwassermollusken aus der Anistratenko V., Peretolchina T., Sitnikova T., Pa­ Rion-Höhle bei Kutais (Transkaukasien, Geor- latov D. & Sherbakov D. 2017. A taxonomic posi- gien). Archiv für Molluskenkunde, 64: 12–14. tion of Armenian endemic freshwater snails of the Sitnikova T.Ya., Peretolchina T.E., Anistraten­ genus Shadinia Akramowski, 1976 (Caenogastro- ko V.V., Anistratenko O.Yu. & Palatov D.M. poda: Hydrobiidae): combining morphological and 2018. Variability and taxonomy of South Cau- molecular evidence. Molluscan Research, 37(3): casian freshwater snails of the genus Shadinia 212–221. https://doi.org/10.1080/13235818.2017. Akramowski, 1976 (Caenogastropoda: Hydrobi- 1279477 idae) based on new morphological and molecular Chertoprud E.S., Borisov R.R., Palatov D.M., Ma­ data. Archiv für Molluskenkunde, 147(1): 63–76. rinskiy V.V., Krylenko S.V., Kovacheva N.P. & https://doi.org/10.1127/arch.moll/147/063-076 Pichkhaia I. 2020. Aquatic macro-invertebrate Starobogatov Y.I. 1962. Contribution to molluscs fauna of caves of Samegrelo-Zemo Svaneti and Ime- from subterranean waters of the Caucasus. Byulle- reti, Western Georgia, Caucasus: troglobiotic and ten’ Moskovskogo Obshchestva Ispytateley Prirody: epigean species complexes. Zoologicheskiy Zhur- Otdel biologicheskiy, 67(6): 42–54. (In Russian). nal, 99(3): 275–289. https://doi.org/10.31857/ Tintilozov Z.K. 1976. The karst caves of Georgia (Mor- S0044513420030058 phological analysis) [Karstovye peshchery Gruzii Glöer P., Bößneck U., Walther F. & Neiber M.T. (morfologicheskiy analiz)]. Tbilisi: Metsniereba. 2015. New taxa of freshwater molluscs from Ar- 276 p. (In Russian). menia (Caenogastropoda: Truncatelloidea: Hydro- Vinarski M.V., Palatov D.M. & Glöer P. 2014. Re- biidae). Folia Malacologica, 24: 3–8. https://doi. vision of ‘Horatia’ snails (Mollusca, Gastropoda, org/10.12657/folmal.024.001 Hydrobiidae sensu lato) from South Caucasus with Grego J., Glöer P., Erőss Z.P. & Fehér Z. 2017. Six description of two new genera. Journal of Natural new subterranean freshwater gastropod species History, 48(37–38): 2237–2253. https://doi.org/10. from northern Albania and some new records 1080/00222933.2014.917210 from Albania and Kosovo (Mollusca, Gastropoda, Vinarski M.V. & Kantor Yu. I. 2016. Analytical cata- Moitessieriidae and Hydrobiidae). Subterranean logue of fresh and brackish water molluscs of Russia Biology, 23(2): 85–107. https://doi.org/10.3897/ and adjacent countries. Moscow: A.N. Severtsov subtbiol.23.14930 Institute of Ecology and Evolution of RAS. 544 p. Grego J., Mumladze L., Falniowski A., Osikow­ Vinarski M.V. & Palatov D.M. 2019. A survey of the ski A., Rysiewska A., Palatov D. & Hofman S. Belgrandiella-like gastropods of the Northern Black 2020. Revealing the stygobiotic and crenobiotic Sea region (Mollusca, Gastropoda, Hydrobiidae molluscan biodiversity hotspot in Caucasus: Part s.l.): morphological variability and morphospecies. I. The Phylogeny of stygobiotic Sadlerianinae Zoologicheskiy Zhurnal, 98(9): 988–1002. https:// Szarowska, 2006 (Mollusca; Gastropoda; Hydro- doi.org/10.1134/S0044513419070122 Received 15 May 2020 / Accepted 22 October 2020. Editorial responsibility: I.A. Ekimova, A.V. Frolov 266 ( Zoosystematica Rossica, Vol. 29, No. 2, pp. 258–266