Not completely lost: two partulid tree snail species persist on the highest peak of Raiatea, French Polynesia

The spectacular partulid tree snail fauna of the Society Islands has been almost completely extirpated in recent decades following the deliberate introduction of the alien carnivorous snail Euglandina rosea. The greatest loss has Occurred oil the island of Raiatea, French Polynesia, home to all estimated 34 species (including 33 single-island endemics), all of which have been deemed extirpated in the wild. However, we report here the February 2006 discovery of two surviving Raiatean partulid lineages oil the upper slopes of Mount Tefatua, the highest peak oil the island. They have been identified using morphological and molecular phylogenetic analyses, the latter approach employing available museum and captive reference samples. One population, at 750 in elevation, consisted of Samoana attenuata. It has a multi-island distribution within the archipelago and surviving populations persist also on Tahiti and Moorea. A second population, present Just below the summit at 950 m, consisted of a previously unstudied morphospecies and it has been formally described as Partula meyeri. It is unclear if a stable altitudinal refuge from E. rosea predation exists oil Mount Tefatua but the unexpected discovery of these two surviving montane populations raises the possibility of preserving some fraction of Raiatea's endemic tree snail diversity in the wild.