THE FINE STRUCTURE OF <i>GYMNODINIUM FUSCUM</i> (DINOPHYCEAE)

Abstract

S ummary The large freshwater dinoflagellate Gymnodinium fuscum (Ehrenberg) Stein, which is the type species of the genus, has flagella, chloroplasts, mitochondria, golgi bodies and chromosomes with typically dinophycean fine structure. It has an elaborate pusule with a large central vesicle, into which numerous small vesicles open, and a spiral canal which connects the central vesicle to the exterior. The nuclear envelope is complex with many flattened vesicles built into it which are perforated only towards the nucleus. The theca consists of three membranes, enclosing beneath the outer two a thin plate‐like structure homologous with the plates of armoured dinoflagellates. Beneath the third membrane numerous microtubules are found. G. fuscum does not possess pyrenoids or trichocysts.