Pseudaphelidium drebesii, genet specnov(incerta sedis), a Parasite of the Marine Centric Diatom Thalassiosira punctigera

Abstract

Pseudaphelidium drebesii genet specnovis a parasite of the centric marine diatom Thalassiosira punctigeraThe motile stage consists of a zoospore with a single opisthokont flagellumIt attaches to a host cell, encysts, penetrates the frustule and develops into a plasmodiumThe plasmodium phagocytizes portions of host cytoplasm which are included in a single big digestion vacuoleAt the end of the trophic phase the plasmodium is a hollow sphere filling the frustule completelyIt cleaves to form ameboid cells which are slowly motile and finally encystThe cysts release 4, sometimes less, zoosporesDiagnoses of genus and species are given, and the uncertain taxonomic position of Pseudaphelidium is discussed.