NEW TAXONOMIC CRITERIA IN CLASSIFICATION OF CHLOROCOCCUM SPECIES. II. PYRENOID FINE STRUCTURE2

Abstract
The pyrenoids of 18 Chlorococcum species (including 3 now transferred to Tetracystis) have been investigated at the ultrastructural level. Three categories of pyrenoids were observed, including pyrenoids with unfragmented perforate starch plates in 11 species; those with many separate fragmented starch plates in 6 species; and those with hemispherical starch plates in 1 species. Pyrenoids were further distinguishable on the basis of the number of thylakoid disks or tubules which penetrate the ground substance. Stability and diversity of pyrenoid fine structure as a taxonomic criterion at the specific level have been demonstrated.