Theodoxus fluviatilis

Wesselingh, Frank, Poorten, Jan Johan ter, Kijashko, Pavel, Albrecht, Christian, Anistratenko, Olga Yu, Frolov, Pavel, Gándara, Alberto Martinez, Gittenberger, Arjan, Gogaladze, Aleksandre, Mikhail Karpinsky, Popa, Luis, Sands, Arthur F, Vandendorpe, Justine & Wilke, Thomas, 2019, Mollusc species from the Pontocaspian region - an expert opinion list, ZooKeys 827, pp. 31-124 : 60-61

Theodoxus fluviatilis (Linnaeus, 1758)

*1758 Nerita fluviatilis Linnaeus: 777.

1865 Theodoxus fluviatilis var. subthermalis Issel: 22-23.

1886 Neritina euxina Clessin: 55.

1908 Neritina danubialis var. danasteri Lindholm: 214-215.

?1972 Theodoxus dniestroviensis Put’: 80-82, text fig. 5.

?1999 Th. dniestroviensis Put’, 1972. - Anistratenko et al.: 19, figs 4, 8.

1999 Th. fluviatilis (Linnaeus, 1758). - Anistratenko et al.: 13-15, figs 3, 4.

2005 Theodoxus fluviatilis (Linnaeus, 1758). - Anistratenko: 7-8, text figs 3, 4.

2012 Theodoxus euxinus (Clessin, 1886). - Welter-Schultes: 27, unnumbered text figures.

2012 Theodoxus fluviatilis (Linnaeus, 1758). - Welter-Schultes: 28, unnumbered text figures.

2015 Theodoxus fluviatilis (Linnaeus, 1758). - Glöer and Pešić: 88-91, figs 1, 3-5, 9, 13-34.

2016 Theodoxus (Theodoxus) fluviatilis (Linnaeus, 1758). - Vinarski and Kantor: 154-155 [pars, excluding synonyms sarmatica and velox ].

2016 Theodoxus (Theodoxus) euxinus (Clessin, 1886). - Vinarski and Kantor: 155.

2016 Theodoxus (Theodoxus) subthermalis (Bourguignat in Issel, 1865). - Vinarski andKantor: 157-158.

Status. Accepted native species.

Type locality. Near Uppsala, Sweden. The lectotype was designated by Anistratenko (2005).

Distribution. Widely distributed all over Europe, Anatolia, and north-western Africa. Within the Pontocaspian region, it is a common component of the lower reaches of Black and Azov Sea drainages (specifically in Bulgaria, Romania, and Ukraine). Towards the east, the species extends at least as far as the Don River system in Russia and the coastal rivers of Georgia, but it is absent from the Caspian system. Records of this species from Iran and western Asia are likely misidentifications (AFS, unpublished data).

Taxonomic notes. Theodoxus fluviatilis exhibits considerable variation in shell colouration and shape ( Glöer and Pešić 2015). Unpublished molecular data confirm the synonymy of a number of taxa such as Theodoxus euxinus syn. n., T. danasteri , and T. subthermalis syn. n., and further suggest the inclusion of T. saulcyi and T. heldreichi (AFS, unpublished data). A final decision concerning the status of T. dniestroviensis Put’, 1972 described from the Dniester River (Rukhotyn village, Khotyn district, Chernivtsi region, Ukraine) is not possible at the moment. Despite appropriate efforts, we were unable to trace the type specimens of this species. Based on the original description and illustration ( Put’ 1972) it was considered as a junior synonym of T. fluviatilis by Anistratenko et al. (1999) having an unusual colour pattern. Theodoxus milachevichi was described as a subfossil from the Crimean coast. It closely resembles morphotypes of both T. fluviatilis and T. velox V. Anistratenko in O. Anistratenko et al., 1999 and might be synonym of either species (compare type material illustrated in Kantor and Sysoev 2006). However, the morphological variability of the taxa involved, as well as the lacking possibility of acquiring genetic data for T. milachevichi , complicates a decision on the independence or synonymy of this species.

Conservation status. Least Concern ( Kebapçı and Van Damme 2012).