A contribution to the knowledge of the water beetle fauna (Col. Hydradephaga, Hydrophiloidea and Staphylinoidea) of a tropical freshwater lake: TasekCini, Pahang, West Malaysia

A recent survey of the water beetle fauna of the alluvial riparian swamp sy stem Tasek Cini in West Malaysia revealed a total of 21 species representin g the families Noteridae, Dytiscidae, Hydrophilidae, Hydraenidae and Hydroc hidae. The Hydrophilidae Helochares ciniensis, H. discus, H. yangae and H. lacustris are described as new, and the male genitalia are figured. The dis tributional range and ecology are discussed for each species. We hen prove that swamp systems such as Tasek Cini hold a comparably rich water beetle f auna adapted to shaded, mesotrophic habitats. Similar ecosystems should be studied elsewhere in Southeast Asia to elucidate actual species ranges and endemicity rates.