Slapcinsky - Diversity of Terrestrial Snails on the Three Largest Islands in the Louisiade Archipelago, Papua New Guinea

Diversity of Terrestrial Snails on the Three Largest Islands in the Louisiade Archipelago, Papua New Guinea

John Slapcinsky

University of Florida, Florida Museum of Natural History, Gainesville, FL 32611-7800, USA, slapcin@flmnh.ufl.edu

The Louisiade Archipelago, a group of volcanic islands and coral islets, with a total area of approximately 1600 km $\mathtwosuperior$, lies about 300 km east of the New Guinea mainland and 400 km west of the Solomon Islands. The Louisiades are at least 15-20 million years old and more likely were formed 40-60 million years ago and have apparently never had a land connection with the New Guinea mainland. The archipelagos physical isolation and great age combine to provide considerable opportunity for the evolution of a distinctive fauna. However, this fauna has remained largely unknown, especially for invertebrates, including terrestrial snails. Only a few brief surveys and small collections made in the mid to late 19^th century lead to the description of the approximately 35 species of land-snails known from the archipelago. Low sampling intensity and poor geographic coverage combined with high levels of endemism suggest that land snail diversity in the archipelago is under-sampled, a view supported by ten weeks of field surveys in January 2003 and April-May 2004 on the three largest islands in the Louisiade Archipelago: Misima (St. Aignan), Vanatinai (Sudest, Tagula) and Yela (Rossel). These surveys uncovered many undescribed snails, nearly all of them endemic to a single island.