A revision of the Pontocaspian gastropods of the subfamily Caspiinae (Caenogastropoda: Hydrobiidae) Author Anistratenko, Vitaliy V. 0000-0003-0832-7625 Department of Invertebrate Fauna and Systematics, Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, B. Khmelnytsky Str. 15, 01030 Kiev, Ukraine. Author Neubauer, Thomas A. 0000-0002-1398-9941 Department of Animal Ecology and Systematics, Justus Liebig University, Heinrich-Buff-Ring 26 - 32 IFZ, 35392 Giessen, Germany. tneub @ zo. jlug. de; https: // orcid. org / 0000 - 0002 - 1398 - 9941 & Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, The Netherlands. tneub@zo.jlug.de Author Anistratenko, Olga Yu. 0000-0003-3655-0701 Department of Invertebrate Fauna and Systematics, Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, B. Khmelnytsky Str. 15, 01030 Kiev, Ukraine. & Department of Cainozoic Deposits, Institute of Geological Sciences, National Academy of Sciences of Ukraine, O. Gontchar Str. 55 b, 01054 Kiev, Ukraine. Author Kijashko, Pavel V. 0000-0002-5270-7900 Zoological Institute, Russian Academy of Sciences, Universitetskaya Emb. 1, 199034 Saint Petersburg, Russia. Author Wesselingh, Frank P. 0000-0002-1868-1815 Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, The Netherlands. & Department of Earth Sciences, Utrecht University, Budapestlaan 17, 3584 CD Utrecht, The Netherlands text Zootaxa 2021 2021-02-19 4933 2 151 197 journal article 8059 10.11646/zootaxa.4933.2.1 1a2ba1ca-028f-4b95-8dda-5ddec4e63524 1175-5326 4550146 5D1D20A5-0F44-4AEF-AF5F-A758FC37D076 Clathrocaspia gaillardi ( Tadjalli-Pour, 1977 ) Figs 9 , 10 Pyrgula ( Caspia ) gaillardi , N. Espece—Tadjalli-Pour 1977: 107, fig. 8. C. [ aspia ] ( Cl. [ athrocaspia ]) gaillardi ( Tadjalli-Pour, 1977 ) — Sitnikova & Starobogatov 1998: 1363–1364 , fig. 1.13. Caspia gaillardi ( Tadjalli-Pour, 1977 ) — Kantor & Sysoev 2006: 87 . Type material. Holotype , Faculté de Médecine Vétérinaire de l’Université de Téhéran ; not studied. One paratype should be in ZIN (“Un spécimen paratype a été déposé au Musée Malacologique de Leningrad ”; Tadjalli-Pour 1977: 107 ), but it could not be found. Type locality. Caspian Sea , Astara-Hachtpar ( Iran ), 0–30 m . Other material. Kantor & Sysoev (2006: 87) were unable to locate identified samples in the ZIN collections, but we retrieved a lot in the Starobogatov collection containing 12 specimens determined as “ Caspia gaillardi ”, collected in the Middle Caspian Basin off Apsheron Peninsula ( Table 1 , locality 13). Additional five specimens come from the South Caspian Basin off Cheleken Peninsula (locality 18, labelled as “ Caspia subgmelini ”) and six specimens derive from late Holocene deposits of the Kura delta (localities 25a and 25f, RGM 1310299–1310304). FIGURE 9. Clathrocaspia gaillardi ( Tadjalli-Pour, 1977 ) from the Middle and South Caspian basins. (a–e) Five specimens from locality 13 (ZIN, no number). (f–i) Three specimens labelled as “ Caspia subgmelini ” from locality 18 (ZIN, no number). (j–n) Five specimens from Holocene deposits of the Kura delta (locality 25d, RGM 1310299–1310303). Scale bar = 1 mm. Description. Shell comparably large, broadly conical, consisting of up to 5 low to moderately convex, slightly stepped whorls. Protoconch bulbous, ranges around 320–335 µm and consists of c. 1.2 whorls; surface strongly sculptured, with distinct wrinkles that increase in size and become more irregular towards teleoconch; final triangu-lar part of protoconch always devoid of wrinkles ( Fig. 10 a–i); additionally, spiral threads occur on first half whorl ( Fig. 10e, g, h ). Teleoconch covered with strong reticulate sculpture, with sharp ribs and subquadrangular interspaces; spirals dominate, axials faintly sigmoid. Aperture ovoid, sometimes detached, leaving slit-like umbilicus; in other cases, basal columellar margin expands beyond columella and covers umbilicus. Remarks. The material in the Starobogatov’s collection fits well to C. gaillardi as described and illustrated by Tadjalli-Pour (1977) , regarding the broad conical shape with five whorls, the marked sutures, the strong sculpture and the comparably large size. Similarly, five specimens labelled in Starobogatov’s collection as “ Caspia subgmelini ” (an unavailable collection name; Fig. 9 f–i) collected off Cheleken Peninsula fit well to C. gaillardi , and so do specimens from the Holocene deposits off the Kura delta ( Fig. 9 j–n). Some of the specimens only have a less stepped spire than is typical of C. gaillardi , but we consider this to range within intraspecific variability. FIGURE 10. Protoconch views of Clathrocaspia gaillardi ( Tadjalli-Pour, 1977 ) from Holocene deposits of the Kura delta. (a, g) RGM 1310299 (locality 25d). (b, h) RGM 1310300 (locality 25d). (c, f) RGM 1310304 (locality 25f). (d) RGM 1310302 (locality 25d). (e) RGM 1310301 (locality 25d). (i) RGM 1310303 (locality 25d). Scale bars = 100 μm. Sitnikova & Starobogatov (1998) provided data on the female reproductive anatomy and the radula of this species. They noted that the studied morphological characters of C. gaillardi and C. gmelinii are almost identical. Also Wesselingh et al . (2019) listed the species as a tentative synonym of C. gmelinii . However, C. gmelinii is much smaller and has a less stepped outline and a weaker reticulate sculpture. Specimens of C. gaillardi also show a certain similarity to C. pallasii , but the latter species can be distinguished by its larger, bulbous protoconch and the more slender shell. The stepped teleoconch of C. gaillardi and the comparably high last whorl also differentiates it from C. isseli . Distribution. Caspian Sea, South Basin to southern part of Middle Basin, known only from shallow waters (max. depth of 44 m ).