<i>GYMNODINIUM ACIDOTUM</i> NYGAARD (PYRROPHYTA), A DINOFLAGELLATE WITH AN ENDOSYMBIOTIC CRYPTOMONAD¹

Abstract

ABSTRACT Ultrastructural examination of the freshwater, blue‐green dinoflagellate Gymnodinium acidotum Nygaard revealed the presence of an endosymbiotic cryptomonad. Features of the endosymbiont allying it with the Cryptophyceae include mitochondria with flattened cristae, paired thylakoids with electron‐dense contents, and nucleomorphs, bodies unique to the Cryptophyceae. This report is the first conclusive documentation of a symbiosis involving these two groups.