DISSODINIUM PSEUDOCALANI SP NOV A PARASITIC DINOFLAGELLATE ON COPEPOD EGGS

In spring 1967 and 1968, a new marine dinoflagellate species, Dissodinium pseudocalani, was discovered off Helgoland in the German Bight. The species lives as ectoparasite on eggs of the copepod Pseudocalanus elongatus. The vesicular parasitic stage adheres to the host by a suction organ. After the substrate of the egg is consumed, the parasite develops into a spherical primary cyst which produces 8, 16 or 32 oval secondary cysts by simultaneous cell divisions. Each secondary cyst forms 16 or 32 dinospores. The dinospores are colourless, flagellated and of the Gymnodinium-type. During reproduction a large reddish or greenish coloured food source is resorbed by the protoplast and diminishes in size. In regard to its mode of reproduction, Dissodinium pseudocalani is related to D. lunula and the parasitic species of Chytriodinium. © 1969 Biologischen Anstalt Helgoland.