Rotifera of some freshwater habitats in the floodplain of the River Nan, northern Thailand

Abstract

A survey of 11 freshwater habitats in the floodplain of the River Nan, northern Thailand was carried out during April and September 1996. The rotifer samples were collected qualitatively from paddy fields, ponds, canals and reservoirs, using a 60 μm mesh net. One hundred and eighteen species were identified, four (Lepadella quinquecostata (Lucks), Macrochaetus danneeli Koste and Shiel, Testudinella ahlstromi Hauer and T greeni Koste) of which are new to Thailand and one (L. quinquecostata) is new to Asia. The numbers of species found in two localities are relatively high, with 86 and 73 rotifer taxa. Most of the species recorded are common, cosmopolitan or pantropical and warm-stenotherms. The occurrence of a species previously considered endemic to Australia, M. danneeli provides more evidence illustrating a relation between the rotifer faunas of southeast Asia and Australia. Comments are presented on some insufficiently known taxa in particular on the new records for Thailand.