A conservation assessment of the freshwater crabs of Sri Lanka

Relative to its size (65,230 km(2)), Sri Lanka has a significantly richer freshwater crab diversity than other tropical Asian countries. Recent and on-going exploration and studies have shown that the island has 51 species of freshwater crabs of the family Parathelphusidae, all of which are endemic, and this number is expected to rise as exploration continues. Approximately 80 % of crab species are restricted to the island's rain-forested south-western 'wet zone' quarter (which includes the central mountains) that, however, represents only a quarter of the territory. High human population density (similar to 700 km(-2)); the survival of only a small extent (similar to 800 km(2)) of undisturbed habitat; extreme fragmentation; and poor sloping-land use practices are identified as the principal threats to Sri Lanka's carcinofauna, together with unregulated pesticide use regimes. The conservation status of each of the 51 species is assessed (based primarily on Extent of Occurrence) against the IUCN (2001) Red List criteria. We conclude that 23 species are Critically Endangered, 8 Endangered, 6 Vulnerable, 8 Near Threatened and 6 Least Concern. The present study is a first step toward developing a conservation strategy for this fauna; the results may be utilized by IUCN for future Red Lists; and for the purpose of developing a conservation strategy for Sri Lanka's threatened carcinofauna.