Epiphytic desmids in the Rosana Reservoir, Paranapanema River Basin, Paraná/São Paulo, Brazil: Euastrum and Micrasterias (Desmidiaceae)

Abstract

Zygnemaphyceae constitutes a class of Green algae that are characterized by a unique mode of sexual reproduction (conjugation) and the absence of flagella in the vegetative and reproductive cells. This class includes representatives which are grouped in two orders, traditionally recognized: Zygnematales or Zygnemales and Desmidiales. Among the families of the Desmidiales, the Desmidiaceae contribute about 70% of the total number of known species. The aim of this study was to inventory the species of Euastrum and Micrasterias of the epiphytic community in the Rosana Reservoir, Paraná/São Paulo, southern Brazil. The samples were carried out in three regions along of the axis the river-dam in the Rosana Reservoir, in April and August 2002. The petioles of Eichhornia azurea Kunth were substrates collected, always in the litoranea region and in all sampling station. Fourteen species were registered, distributed in Euastrum (six) and Micrasterias (eight). Comparing the two samples in different regions of the Reservoir, highest species richness was recorded in the hot period (April).