Diversity and phylogeny of marine parasitic dinoflagellates

Abstract

The dinoflagellates are an assemblage of autotrophic, myxotrophic and heterotrophic species and play important roles in marine ecosystems. Most of them are free-living, but several are known as symbionts of marine invertebrates or as parasites of aquatic animals and protists. Molecular phylogenetic studies on parasitic dinoflagellates reveal that the parasitism has evolved polyphyletically appearing several times independently within the division Dinophyta. The Dinophyta consists of "core" dinoflagellates (typical dinoflagellates) and "basal" dinoflagellates. Within the basal dinoflagellates, the parasitic clades of Perkinsea, Ellobiophyceae and Syndiniophyceae are recognized. A large portion of environmental clone sequences recovered from various parts of the oceanic environments are thought to be members of the parasitic order Syndiniales (Syndiniophyceae). Therefore, the ecological function of parasitic dinoflagellates in the ocean is now better understood. The members of parasitic genera such as Parvilucifera (Perkinsea) and Amoebophrya (Syndiniophyceae) infect other dinoflagellates; therefore, much attention has been paid, because of their possible ability to control harmful algal blooms (HABs). The parasitism has also evolved within the "core" dinoflagellates (Dinophyceae) a number of times. These include Blastodinium , Chytriodinium , Dissodinium , Haplozoon , Oodinium , Paulsenella and Tintinnophagus. Because there are already several reviews on diversity of parasitic dinoflagellates, in this volume, only recent developments in phylogenetic studies on parasitic marine dinofl agellates are mainly reviewed here.