Introduced land molluscs on the islands of the Tristan da Cunha - Gough group (South Atlantic)

Three introduced species of land snail (Oxychilus alliarius, Vitrea contrac ta and Lauria cylindracea) and five species of slug (Deroceras reticulatum, D. laeve, D. panormitanum, Milax gagates, Lehmannia valentiana) are report ed from islands in the Tristan da Cunha - Gough group. All eight species we re found on Tristan da Cunha itself, the largest island and the one most se verely affected by human disturbance. A few, notably Oxychilus alliarius, D eroceras reticulatium, D. laeve and D. panormitanum, have also been found o n some of the other islands, where they have spread into various communitie s of native vegetation. On Inaccessible Island, O. alliarius occurred in so me peculiar habitats, including dried holdfasts at the top of the boulder b each. These introduced species have western Palaearctic origins but are lik ely to have reached the Tristan - Gough islands with supplies imported via South Africa.