Abstract
Direct observation as well as culture experiments revealed Dissodinium pseudolunula as an ectoparasite on eggs of the marine planktonic copepod Temora longicornis. The vegetative life cycle, especially the parasitic phase, which involves phagocytosis, is reported for the first time. The species resembles D. pseudocalani, which is also parasitic upon copepod eggs. The taxonomic position and the survival of D. pseudolunula during the absence of the host in the winter is discussed.