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

Taehwan Leea1, Jean-Yves Meyera2, John B. Burcha1, Paul Pearce-Kellya3 and Diarmaid Ó Foighila1 c1

a1 Museum of Zoology and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109-1079, USA.

a2 Délégation à la Recherche, Ministère de l'Education, de l'Enseignement Supérieur et de la Recherche, B.P. 20981 Papeete, Tahiti, Polynesie Française.

a3 Zoological Society of London, Regent’s Park, London, NW1 4RY, UK.

Abstract

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 on the island of Raiatea, French Polynesia, home to an 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 on the upper slopes of Mount Tefatua, the highest peak on 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 m 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 on 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.

(Received August 10 2007)

(Reviewed October 16 2007)

(Accepted January 07 2008)

Correspondence:

c1 Museum of Zoology and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109-1079, USA. E-mail diarmaid@umich.edu

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