The systematic position of the parasitoid marine dinoflagellate Paulsenella vonstoschii (Dinophyceae) inferred from nuclear-encoded small subunit ribosomal DNA.

Members of the genus Paulsenella Chatton are marine phagotrophic dinoflagellates that specifically attack marine diatoms. In this phylogenetic study, we show that Paulsenella groups with Amyloodinium ocellatum (Brown) Brown et Hovasse, Pfiesteria piscicida Steidinger et Burkholder (Dinophyceae), Pfiesteria shumwayae Glasgow et Burkholder, and the cryptoperidiniopsoids, all members of the order Peridiniales. In the phylogenetic tree, Paulsenella diverged after Amyloodinium ocellatum but prior to Pfiesteria and the cryptoperidiniopsoids. This suggests that Paulsenella also belongs to the order Peridiniales and its earlier description as gymnodinioid and athecate has to be revised.