Checklist and distribution of the land and freshwater molluscs from north-western Italy (Piedmont, Valle d’Aosta and Liguria)

This checklist of terrestrial, freshwater and brackish-water molluscs of Piedmont, Valle d’Aosta and Liguria (NW Italy) is based on literature and museum data and on research by the authors and co-workers carried out until the end of 2020. The malacofauna consists of 394 taxa (280 land and 114 aquatic molluscs), 308 for Piedmont (225 land and 83 aquatic), 139 for Valle d’Aosta (120 land and 19 aquatic) and 274 for Liguria (193 land and 81 aquatic) and includes 24 undetermined or undescribed species and 44 endemics, 27 of which have a very narrow range. Three species are particularly localized: Iglica pezzolii Boeters, 1971, and Chondrina feneriensis Bodon, Nardi, Cianfanelli & Kokshoorn, 2015, limited to Monte Fenera (Novara and Vercelli provinces), and Falkneria camerani (Lessona, 1880), known from a few localities in the Pennine Alps. Seven taxa, recorded in the past, were no longer found: Eupaludestrina stagnorum (Gmelin, 1791), Marstoniopsis insubrica (Küster, 1853), Orcula dolium dolium (Draparnaud, 1801), Leucostigma candidescens (Rossmässler, 1835), Zonites algirus (Linnaeus, 1758), Cochlicella conoidea (Draparnaud, 1801) and Pisidium moitessierianum Paladilhe, 1866. Several species are of conservation interest according to the European Red List of non-marine molluscs and the IUCN Red List of terrestrial gastropods: one of these, Renea bourguignatiana Nevill, 1880, present in Italy in a few sites near Ventimiglia, is considered Critically Endangered; five others are reported as Endangered and 13 as Vulnerable. Among the threatened species, two have a very narrow range: Alzoniella delmastroi Bodon & Cianfanelli, 2004, limited to the Turin area and Pezzolia radapalladis Bodon & Giusti, 1986, known only in eastern Liguria from Recco to Rapallo (Genoa province). Finally 46 entities are aliens, including three recently reported in Italy: Zonitoides arboreus (Say, 1817), Boettgerilla pallens Simroth, 1912 and Deroceras sturanyi (Simroth, 1894)