Diversity and conservation of the land snail fauna of the western pacific islands of belau (republic of palau, oceania)

Pacific land snails are among the most threatened animals on Earth, and basic information on the number of extant species is lacking for many island groups. The isolated western Pacific archipelago of Belau comprises 586 islands, most of which have suitable land snail habitat; yet little has been published on the land snail fauna. I undertook surveys throughout Belau, searching trees and emergent vegetation, leaf litter, and limestone rock. Survey results from selected, geographically representative islands are presented here. The total number of species found in these areas (117) indicates that there may be ca. 200 extant Belau land snail species. This number far exceeds previous estimates. Most species are endemic to Belau (95% in this survey), and species endemic to one or a few islands are not uncommon. Leaf litter and rock dwelling diplommatinid land snails are a large component of the snail biota: only 26 Belau diplommatinids have been described, and 81 species were collected in this survey. Although caenogastropod land snails comprise the most obvious portion of the fauna, notable pulmonates include the partulids and endodontoids, two land snail groups that have suffered extinction throughout the Pacific region. Belau has one of the most spectacularly diverse extant land snail faunas in the Pacific region, and the restricted ranges of many species highlight the need for conservation attention, particularly on the island of Babeldaob, which is undergoing increased deforestation.