Comparative ultrastructure of underlayer scales in four species of the green flagellate Pyramimonas: a freeze-fracture and thin section study

Abstract

The detailed ultrastructure of underlayer scales has been investigated in four species of the prasinophycean flagellate Pyramimonas: P. amylifera, P. obovata, P. grossii and P. parkeae. The use of deep-etching of living cells and tannic acid staining for thin sections led to a better preservation of structural details compared to previously used methods of study. Three of the four species exhibited differences in the detailed structure of the cell body underlayer scales, only the underlayer scales of P. grossii and P. parkeae were indistinguishable. The differences found included scale size, vertical height of lateral rims, presence or absence of a central boss and its detailed structure, and the surface structure of the lateral rims of the scale. In contrast to body scales underlayer scales on the flagella were practically indistinguishable in the four species studied. The taxonomic significance of underlayer scales in the genus Pyramimonas and their phylogenetic significance in the green algae are discussed.