v1i2.21

Submitted date: 15 June 2009
Accepted date: 15 October 2009
Published date: 22 November 2009
Pp. 130–134.

DISTRIBUTION PATTERNS OF THE GENUS Paludomus (GASTROPODA : THIARIDAE : PALUDOMINAE) IN MAHAWELI, KELANI, KALU, GIN AND MAHA-OYA RIVER BASINS OF SRI LANKA

A.A. Thasun Amarasinghe* & S.R. Krishnarajah
*Corresponding author. E-mail: thasun.taprobanica@gmail.com

Abstract
Since the publication of Preston’s Fauna of British India – Freshwater Gastropoda and Pelcypoda in 1915, a vast amount of knowledge has accumulated on the fresh water molluscs. Starmühlner (1974) published a monograph on the fresh water gastropods, in which he listed 31 species of freshwater snails from Sri Lanka. Until the early 20th century, malacologists used mainly conchological characters to describe species. However, the shells of freshwater gastropods are highly variable, show ecological plasticity, and are known to suffer from convergence and homoplasy, and therefore do not always reliably reflect systematic boundaries. It is already known that other groups of freshwater organisms in Sri Lanka including fish and crabs show high levels of endemism within individual river basins. It remains to be discovered whether molluscs too, show such basin-level endemism. These studies also found that there was significant altitudinal stratification and basin-level endemism of species, a factor that remains to be assessed for aquatic molluscs. In order to address these questions, and assess the diversity of this fauna, we surveyed the freshwater mollusc fauna (focusing mainly on the genus Paludomus) in the Mahaweli, Kelani, Kalu, Gin and Maha-Oya River basins of Sri Lanka. A total of 10 morphospecies were recorded, based on examination of 20 specimens of each species from 20 locations in the altitude range 100-2000 m above mean sea level. Species-level identification is in progress, and further surveys are needed to assess the full diversity of this important fauna.

Key words : aquatic conservation, distribution, freshwater gastropods

Section Editor: Brenden Holland