LIGHT AND ELECTRON MICROSCOPY OF A PUNCTATE SPECIES OF PYRAMIMONAS, P. MUCIFERA SP. NOV. (PRASINOPHYCEAE)

Pyramimonas mucifera sp. nov., a punctate species of the genus, is unusual both behaviorally and at the fine structural level. It forms two distinct populations in culture, one benthic and one planktonic. Planktonic forms are more conventional for the genus, but benthic forms are found in loosely packed mucilage, have flagellar rather than ciliary beating of the flagella, and display a higher degree of metaboly. Ultrastructurally this species is unusual in that it has a unique scale complement and the cells contain numerous muciferous vesicles, leaving only small pockets of cytoplasm containing the usual organelles. This species has a 3-1 type flagellar apparatus but has an additional fibrillar band, a 4-3-2-3 microtubular root system and a flexible synistosome.