Turbo bidens Linnaeus 1758 (Gastropoda: Clausiliidae) misidentified for 250 years

The nomenclatural history and the identity of the nominal species Turbo bidens Linnaeus 1758 (Gastropoda: Pulmonata: Clausiliidae) is discussed. It is shown that it has been incorrectly identified with the species known as Papillifera papillaris (O.F. Müller 1774) based on a misinterpretation of the original diagnosis. As the name has been placed on the Official List in Opinion 2176, it requires a valid neotype designation to fix its identity in an unequivocal manner. It is shown that the neotype designation by Falkner et al. (2002) is invalid. A neotype is proposed, which will render the name Turbo bidens Linnaeus 1758 a senior subjective synonym, and the valid name for the species hitherto known as Cochlodina (Procochlodina) incisa (Küster 1876). The nominal species Turbo bidens Linnaeus 1758 has been cited as the type species of Clausilia Draparnaud 1805, Cochlodina Férussac 1821 and Marpessa Gray in Turton 1840, but in all cases Turbo bidens Linnaeus 1758 was misidentified. The type species of Papillifera Hartmann 1842 is usually assumed to be Clausilia solida Draparnaud 1805 through subsequent designation by Lindholm (1924), but the earlier designation of Helix papillaris O.F. Müller 1774 by von Martens 1860 is shown to be valid.