ABSTRACT
The class Prochlorophyceae1 was formed to contain one species, the coccoid ascidian epibiont Prochloron didemni Lewin (Synechocystis didemni Lewin2). Ascidian endosymbionts that had been discovered (but not formally described) at around the same time3 soon came to be regarded as also belonging to the genus Prochloron, but no further species, as yet, have been erected.
