in Sri Lanka - Ministry of Environment

pulmonates, namely Ravana, Ratnadvipia, Acavus, Oligospira and cyclophorid prosobranchAulopoma. These species show discontinued distribution and are restricted to few specifichabitats in the wet and southwestern portion of the island (Raheem, 2000).Of the land snail genera recorded from the island, 13 (Ruthvenia, Thysanota, Cryptozona,Euplecta, Mariaella, Eurychlamys, Corilla, Beddomea, Trachia, Leptopomodes, Micraulax,Tortulosa and Nicida) are restricted to Sri Lanka and Peninsular India, primarily to WesternGhats; approximately 50% of the 253 species recorded from the island belong to generaendemic to southern India and Sri Lanka. About 18 exotic land snails and slug species, mostof which are agricultural pests, have also been recorded from the country during recent studies(Naggs et al., 2003). However, this has increased up to 21 species according to the mostrecent information.Studies done by Raheem et al. (2000) and Ranawana (2005) showed that the lowland rainforestzone and the montane rainforest zone in Sri Lanka have distinctive snail faunas. The lowlandrainforest fauna is composed of a widely distributed element and a localized or restrictedrangecomponent. Widely distributed lowland rainforest species include Cryptozona chenui,Ratnadvipia irradians, Acavus phoenix, Corilla adamsi, Beddomea albizonatus aggregate andLeptopoma semiclausum. These taxa range across most or all of the forested areas of thelowland wet zone while some species such as Ratnadvipia irradians occur in both forest andnon forest habitats (Raheem et al., 2000).ThreatsMolluscs, together with other animals and plants, are facing a rapid process of extinction largelydue to human activities, and the present extinctions of species occur in time spans of lessthan ten years (Kay, 1995). Majority of the terrestrial molluscs are forest dwellers, sensitiveto habitat disturbance. Therefore, from the biodiversity conservation point of view they are ofregional and global concern (Emberton, 1995; Tattersfield et al., 2001).Habitat loss is the main threat faced by land snails in the country. Highly diverse areassuch as lowland rainforests of the wet zone of the country are highly fragmented. Groundcover of the mountain regions such as in the Knuckles Region are cleared for cardamomcultivation. Most of the land snails are leaf litter inhabitants, thus clearance of forest flooris detrimental to their survival. Vast area of land in the wet and dry zones of Sri Lanka wasinundated due to large scale dam construction for river diversion (especially the Mahaweliriver) and hydroelectric generation. These development activities cause loss of habitats, eitherminimize the area available for a species or completely wipe out a species from a locality.Frequent fires in the grasslands, scrublands and forests are detrimental to the survival of landsnails. This is evidenced by the record of very few snail species from the grasslands, whererepeated fires occurs. Use of agrochemicals is also harmful to native land snail species foundin association with human settlements. Species belonging to endemic genera such as Acavusand Ratnadvipia, found in synanthropic habitats are severely affected by agrochemicals.66