Variation in Valve Morphology During the Life Cycle of the Marine Diatom Coscinodiscus concinnus

Abstract In cultures, three morphological phases can be recognized during the life cycle of Coscinodiscus concinnus W. Smith. Shells of the post-auxospore phase are typical of C. concinnus. Shells of the intermediate phase are typical of C. granii Gough. Shells of the pre-auxospore phase possess a distinct morphology which has not heretofore been described. Of the two validly published names which have been applied to different stages in the life history of this species C. concinnus W. Smith (1856) takes priority over C. granii Gough (1905) as the correct name.