Another Case of Phagotrophy by Gymnodinium helveticum Penard f. achroum Skuja

Several new details in the behaviour of Gymnodinium helveticum fo. achroum Skuja during phagotrophic feeding were described. Diatom cells entered the Gymnodinium by means of a lobopode extruding from the sulcus. During phagotrophic feeding, a cone shaped nucleus is closely attached to the food vacuole in the epicone. It is suggested that this Gymnodinium exhibits probably selective phagotrophy. The systematic position of the dinoflagellates is discussed. In the case of Katodinium spirodinioides Christen a motionless stage with numerous rhizopodia was observed. Pumping of diatom cell contents with the help of rhizopodia was noticed. A possible relationship between Katodinium spirodinioides Christen and present “Cystodinedria” cells is discussed.