Studies in the Fine Structure and Taxonomy of Flagellates in the GenusPavlovaI. A Revision ofPavlova Gyrans, The Type Species

Abstract

When first described, as the type species of a new genus (Butcher, 1952), Pavlova gyrans was thought to be separable from Ochromonas by only one major character, namely the lateral instead of the supposedly terminal insertion of the strongly anisokont flagella. It was therefore natural to include it in the class Chrysophyceae and to interpret other structural features in accordance with this view. This practice has been continued to some extent subsequently and the three named species which are now recorded in the literature are all in varying degrees in need of emended descriptions. For this particular genus is deceptive. Not only are there unusual fixation difficulties, as already noted by Butcher, but even when examined alive its appearance can suggest the presence of characters which are not in fact what they seem to be and mask others which are essential for taxonomic guidance. Even when all these difficulties have been overcome, certain details are so unusual as to be without known parallel among the ‘brown’ flagellates which have so far been studied with the electron microscope.