Three introduced species of land snail (Oxychilus alliarius, Vitrea contracta and Lauria cylindracea) and five species of slug (Deroceras reticulatum, D. laeve, D. panormitanum, Milax gagates, Lehmannia valentiana) are reported from islands in the Tristan da Cunha - Gough group. All eight species were found on Tristan da Cunha itself, the largest island and the one most severely affected by human disturbance. A few, notably Oxychilus alliarius, Deroceras reticulatum, D. laeve and D. panormitanum, have also been found on some of the other islands, where they have spread into various communities of native vegetation. On Inaccessible Island, O. alliarius occurred in some peculiar habitats, including dried holdfasts at the top of the boulder beach. These introduced species have western Palaearctic origins but are likely to have reached the Tristan - Gough islands with supplies imported via South Africa.
Tristan da Cunha
introduced land molluscs