Some Affinities Of The Raphidophyceae With Other Chromophyte Algae

Abstract Some characteristics of the raphidophycean genera, Chattonella, Fibrocapsa, Gonyostomum, Heterosigma, Merotricha, Olisthodiscus, and Vacuolaria are reviewed to determine possible affinities with other members of the Chromophyta. Information from ultrastructure, cell biology, and molecular biology indicates both shared features within the Chromophyta (for example, presence of chlorophylls a, c  1, c  2 arrangement of thylakoids, tubular ciliary hairs, tubular nature of the mitochondrial cristae), and features apparently characteristic of the Raphidophyceae, for example, the layered structure component of the cytoskeleton which does not appear to occur in other Chromophyta. The layered structure, the complex arrangement of the rhizoplast and rhizostyle, and the absence of a transitional helix mean that the cilia and their associated cytoskeleton present a distinctive combination of features that should be useful in defining the Raphidophyceae.