ATYPICAL CAROTENOIDS FOR THE RHODOPHYCEAE IN THE GENUS GRACILARIA (GIGARTINALES)

It is generally accepted that the carotenoids of the rhodophycean algae are .alpha.-carotene, .beta.-carotene, lutein and zeaxanthin. One report on a species of Gracilaria indicated that antheraxanthin, an epoxide, was the major carotenoid. This report is confirmed and 21 other samples (mostly unialgal cultures, some field material) representing at least another 8 spp. of Gracilaria are examined. All samples contained antheraxanthin and many also had the diepoxide, violaxanthin. This is the 1st report of the latter compound for this genus. Data indicate that carotenoid epoxides are probably more common in the Rhodophyceae than is generally indicated, and phylogenetic schemes based on pigment composition must be modified accordingly to accommodate these compounds in the Rhodophyceae.