THE TRIDENTATA PARASITE OF MALLOMONAS-TEILINGII (SYNUROPHYCEAE) - A NEW DINOPHYTE - OR WHAT

A light and electron microscopic investigation of an organism parasitizing the chrysophyte Mallomonas teilingii, ingesting its cytoplasm and organelles. Its life history has been followed, including infection, growth, encystment, and swarmer formation. Its taxonomic allocation is discussed, especially whether it has affinity to either zoosporic fungi or to dinophytes. However, on the basis of cell organization, deposition of starch granules, presence of an accumulation body, and construction of the cyst wall it is preliminarily suggested to have a dinophyte affiliation, although a typical dinocaryon is not present, and it is compared with various aberrant parasitic dinophytes. On the whole, however, the evidence is conflicting, and for the present it will be placed as an organism incertae sedis, formally described as a new genus, Phagodinium, with one species, P. tridentatum.