Ecology and distribution of freshwater crabs in Knuckles mountain range of Sri Lanka

Abstract

Ten species of freshwater crabs, which belong to four genera, have been so far identified from the Knuckles mountain range These are Ceylonthelphusa rugosa, C. sorror, C. sanguinea, C. callista, C. cavatrix, C sentosa, C. armata, Pcrbrinckia nana, Oziothelphusa stricta and Mahala adonis. These four genera belong to the family Parathelphusidae

Ceylonthclphusa rugosa, C. sorror, C. sanguinea and C. callista show a wide range of distribution within the Knuckles area. C. rugosa and C sorror being more abundant at lower altitudes. while C sanguinea, C. callista, and C. cavatrtx being more abundant at higher altitudes.

Usually C. rugosa and C. sorror are found in stagnant pools, whereas C. sanguinea and C. callista prefer semi-terrestrial habitats. Sometimes, the latter two species are found under stones or in leaf litter, away from a water sources C sanguinea is also found under stones in wet places. especially where water is oozing over the surface. No other crab species was observed in such habitats during the present study. C. cavatrtx is usually found under wet soil and moist stones along the banks of the streams, but during the present study, a large number was observed in a small stagnant pool as well C. armata was found under stones in a marshy area adjacent to a small stream near a tea plantation Oziothelphusa stricta was observed in holes lT1 the hanks of a stream near a paddy fieid 0. stricta and Mahata adonis are burrowing forms.

During the present study, new locality records of the different species of crabs were made as follows C. seutosa at Kandaketiya Estate near the township of Huluganga, (previously recorded only from the type locality at Kottawa Proposed Forest Reserve in Gaile District), Pcrbrinckia nana at Narangarnuwa near Lakegala, (previously recorded from three locations in South-western Sri Lanka within the Beruota and Gin river basins), C armetta at Kabaragala near Madulkele, (previously recorded onlv from its type locality near Galawidaputena- Kadugannawa beside Kandy road), C cavatrix at Narangamuwa near Pallegama (previously recorded from a different nearby drainage system), Oziothelphusa stricto at Narangarnuwa (previously recorded from some areas of the dry zone and some parts of the Knuckles area), Mahata adonis at Rambukoluwa near Pallegama (previously recorded from some other locations of Knuckles area, and also from the southern parts of the dry zone)