Oceanic islands frequently support endemic faunal radiations that are highly vulnerable to introduced predators [1]. This vulnerability is epitomized by the rapid extinction in the wild of all but five of 61 described Society Islands partulid tree snails [2], following the deliberate introduction of an alien biological control agent: the carnivorous snail Euglandina rosea[3]. Tahiti's tree snail populations have been almost completely extirpated and three of the island's eight endemic Partula species are officially extinct, a fourth persisting only in captivity [2]. We report a molecular phylogenetic estimate of Tahitian Partula mitochondrial lineage survival calibrated with a 1970 reference museum collection that pre-dates the predator's 1974 introduction to the island [4]. Although severe winnowing of lineage diversity has occurred, none of the five primary Tahitian Partula clades present in the museum samples is extinct. Targeted conservation measures, especially of montane refuge populations, may yet preserve a representative sub-sample of Tahiti's endemic tree snail genetic diversity in the wild.