A floristic survey was based on the study of 148 sample units, from which 75 were already deposited at the Herbário Científico do Estado “Maria Eneyda P. Kauffmann Fidalgo” of the Instituto de Botânica, São Paulo State Department of Environment, and 73 were collected during the period 2000-2001. Three taxa of Octacanthium (Desmidiales, Zygnemaphyceae) were identified: O. bifidum (Brébisson) Compère var. bifidum, O. mucronulatum (Nordstedt) Compère var. mucronulatum, and O. octocorne (Ralfs) Compère var. octocorne.
Taxonomy; floristic survey; biodiversity; algae; Brazil