SCALE STRUCTURE IN MANTONIELLA-SQUAMATA, WITH SOME COMMENTS ON THE PHYLOGENY OF THE PRASINOPHYCEAE (CHLOROPHYTA)

Mantoniella squamata (Prasinophyceae, Chlorophyta) is presently considered to be one of the most primitive green plants. The structure of the spider-web-like scales that cover the flagellar and body surfaces of this organism is described. By contrast to current theory, the scales may be divided into several different morphological types, one form being restricted to the flagella and two to the cell body. The cells contain trichocyst-like organelles similar to those found in the related species Mamiella gilva. In the order Mamiellales, which contains four genera and seven described species, the simplest and thus perhaps the most primitive species is the recently described Bathycoccus prasinos Eikrem et Throndsen, the cells of which lack flagella and are covered with only one type of plate scale.