Further Observations on the Type Subgenus Ofpyramimonas(prasinophyceae), with Particular Reference to a New Species,p.chlorina, and the Flagellar Apparatus Ofp.propulsa

A new quadriflagellate species of Pyramimonas isolated from South African inshore waters is described. It has ultrastructural features most consistent with the subgenus Pyramimonas McFadden. The flagellar apparatus of this organism is basically of the 3-1 type, but a unique structure, which may be considered a homologue of the R2-associated fiber found in Pterosperma cristatum, is associated with the 1s root. It thus could be construed as an alternate primitive form of the genus to Pyramimonas mucifera Sym & Pienaar. The flagellar apparatus of Pyramimonas propulsa Moestrup & Hill has surprising differences to that of Pyramimonas octopus Moestrup. Hori, & Kristiansen, particularly with regard to the microtubular roots and the distal fibrillar bands. Features of these two species, together with those extracted from the literature, show a considerable overlap between the subgenera Pyramimonas and Punctatae but, ironically, it is considered inappropriate at this time to combine the two subgenera because of anomalies exhibited by the new species. Key words: flagellar apparatus, Pyramimonas subgen. et gen., P. chlorina sp.nov., P. longicauda, ultrastructure.