Ultrastructure and taxonomic position of Chlorosarcina stigmaticaDeason (Chlorophyceae, Chlorophyta)

Abstract

Using cryofixation methods we studied the ultrastructure of thallus cells and zoospores of a chlorosarcinoid alga present in the Innsbruck culture collection (strain nr. T 105). We confirm an earlier observation by Gärtner et al. (1988) that pyrenoids are absent, and that it represents Chlorosarcina stigmatica Deason 1959. This species was recently transferred to another genus because descendents of the original culture were found to possess pyrenoids. Our observations on T 105 demonstrate however that the original concept of C. stigmatica as a species of Chlorosarcina (a genus characterized by the absence of pyrenoids) is still valid. We found the zoospore flagellar apparatus to be characteristic of the class Chlorophyceae sensu Mattox and Stewart . Other species, i.e. C. brevispinosa and C. longispinosa are known to have an ulvophycean flagellar apparatus. It is proposed to transfer these to a separate new genus, Pleurastrosarcina , in the class Ulvophyceae.