A revised classification of Cryptophyta

Abstract

The systematics of currently recognized cryptomonad genera is reviewed. Complete ultraÍstructural descriptions are provided for each genus, and are based on the most recent observations in the literature. Using ultrastructural, biochemical and molecular data, a classification scheme, which delineates 16 genera, is proposed for the Cryptophyta. This scheme accommodates two classes, the Cryptophyceae and the Goniomonadea. These differ primarily in that the former possesses a plastidial complex whereas the latter lacks one. Three orders are discussed and are separated on the basis of colour. The order GonioÍmonadales, which consists of a single genus, is aplastidal and colourless. The order Cryptomonadales has two families and contains the accessory pigment Cr-phycoerythrin 566 which imparts a brown colour to the cells. The constituent families, Cryptomonadaceae and Campylomonadaceae, are separated by variations in the furrow/gullet complex, the inner periplast component (IPC), nucleomorph position, and the type of rhizostyle. The order Pyrenomonadales contains four families. It is the sister group to the Cryptomonadales and possesses the accessory pigments Cr-phycoerythrin 545, 555, and these impart a red colour to the cells, or other members that possess Cr-phycocyanin 630, 645, or 569, which impart a blue-green colour to the cells. The four families are separated on the basis of phycobiliprotein type and, where appropriate, a combination of nucleomorph placement, type of IPC, rhizostyle type, and furrow plate type. This scheme accommodates three new families, the Campylomonadaceae, Geminigeraceae, and Chroomonadaceae.