Sterols and fatty acids of three harmful algae previously assigned as Chattonella.

Sterol and fatty acid compositions were determined for three harmful algal species previously classified in the genus Chattonella (Raphidophyceae): the new genus Chloromorum toxicum (ex Chattonella cf. verruculosa), Verrucophora farcimen (Dictyochophyceae), previously Chattonella aff. verruculosa, and Verrucophora verruculosa (=Pseudochattonella verruculosa) previously Chattonella verruculosa. The major fatty acids of C. toxicum were 14:0, 16:0, 18:1n-9, 18:4n-3 and 20:5n-3, and those of the Verrucophora strains were. 14:0, 16:0, 18:0, 18:4n-3, 18:5n-3 and 22:6n-3. C. toxicum contained the 24beta-ethyl sterols, poriferasterol and clionasterol, as its major sterols. For comparison, the stereochemistry of the 24-ethyl sterols of two raphidophytes, Chattonella marina and Heterosigma akashiwo, was determined to be 24alpha and 24beta, respectively. Both Verrucophora strains contained the 27-nor sterol occelasterol as the only detected sterol. This was the first time occelasterol has been found in algae.