Terrestrial Mollusks of Roadside Biotopes in the Western Caucasus: A Transport Vector for Distribution into Other Regions

The dispersal of alien species often occurs via road and rail transport. Although snails and slugs are slow-moving animals, many species of terrestrial mollusks can survive such transport and can therefore cover long distances. The Caucasus is a source region for alien snails and slugs in European Russia and adjacent territories not only owing to the rich biodiversity but also owing to the well-developed transportation network. In this study, roadside biotopes along railways and highways in the Republic of Adygea and Krasnodar Territory were surveyed and the diversity of the mollusk communities was assessed. Six species of terrestrial mollusk were found along both roads and railways, with the number of individuals in a single area reaching 110/m². The most abundant was the steppe species Xeropicta derbentina. Land mollusks are 1.84 times more likely to be found along railways than along roads, as confirmed by regression analysis (p = 0.001). These results confirm the association of several Caucasian land mollusks with road infrastructure biotopes.