SOME RARE AND INTERESTING PLANKTON ALGAE FROM SRI-LANKAN RESERVOIRS

This paper constitutes a floristic study of phytoplankton net samples taken from 9 reservoirs during the period May to October 1982. More th an 100 taxa were identified belonging mainly into three taxonomic grou ps: desmids, cyanophytes, and chlorophytes (mainly order Chlorococcale s). The largest portion of species (50%) is cosmopolitan, whereas 20% show a tropical and warm temperate distribution and only 10% are known to be tropical. The group of the rare desmid taxa comprises the large st portion of mainly tropical species (approx. 40%). The taxonomic pos ition of most species is discussed and a large portion (60%) is illust rated.