Diadesmis confervacea (Diadesmiaceae-Bacillariophyta): external morphology, distribution and ecological aspects

This paper gives information about the external morphology, distribution and ecology of Diadesmis confervacea (Grunow) Hustedt, based on material collected in freshwater environments from the Coastal Plain of southern Brazil. The species was found solitary and colony-forming within the plankton and metaphyton of lakes, a marshe and a pond, often in slightly acidic water (pH 6,2-6,6) whose conductivity was high (>110 kS.cm super(-1)) and temperature within 14 and 24C. The striae density observed were similar to those individuals that were found in some lotic environments from Brazil and southern Africa. The valves ultrastructure was similar to the specimens that were cultivated in the United States, only differing by the lack of irregular granules on the mantle.