The Eunotiaceae study in several environments (lakes, swamps and dams) in the Costal Plain of Rio Grande do Sul State was carried out in the autumn and the spring of 2003. Twenty six specific and infra-specific taxa were identified, one belonging to Actinella and twenty five to Eunotia. The highest richness of Eunotia species was reported in the swamps where we found a lush marginal vegetation and more acid water (pH 4,3 and 5,4). Eunotia bilunaris (Ehr.) Souza, E. tridentula Ehr. var. tridentula, E. vumbae Choln., E. yberai Freng. and E. zygodon Ehr. are new records for the Coastal Plain of Southern Brazil. The species are described, commented, and illustrated in light microscope (LM) and/or in scanning electron microscope (SEM).
diatoms; geographical distribution; subtropical climate; taxonomy
