CHLOROPLAST PIGMENT PATTERNS IN DINOFLAGELLATES 1

SUMMARY The chlorophylls and carotenoids of 22 species of dinoflagellates were analysed by thin layer chromatography, using 2‐dimensional sucrose plates, and 1‐dimensional polyethylene plates for chlorophylls c 1 and c 2 . Peridinin was the major carotenoid in 19 of the species, while fucoxanthin was the major carotenoid in 3. In the peridinin‐containing species, 5 carotenoid fractions, constituting more than 95% of the total carotenoids, were always present. These were peridinin (± neo‐peridinin), averaging 64% of the total carotenoid, diadinoxanthin, dinoxanthin, β‐carotene and a polar, unidentified pink xanthophyll. Six other carotenoid fractions occurred in minor or trace quantities among the species, but were not identified. Two of these had, a wide distribution; the other 4 were restricted to one or 2 species. The chlorophyll content of the dinoflagellate cultures ranged from 1–141 μg chlorophyll a + c/10 6 cells, a pattern which was broadly correlated with cell size. In the peridinin‐containing species the ratio of chlorophyll a to c on a molar basis was approximately 2 (range 1.60–4.39); in the fucoxanthin‐containing species this ratio was approximately 4 (range 2.65–5.73). Both chlorophylls c 1 and c 2 occurred in the fucoxanthin‐containing dinoflagellates, and only chlorophyll c 2 (one exception) occurred in the peridinin‐containing dinoflagellates. These patterns of chlorophyll c and major carotenoid correspond to patterns previously observed in the Pyrrhophyta and the Chrysophyta, suggesting different phylogenetic origins for the “dinoflagellate” chloroplasts.