THE ULTRASTRUCTURE AND LIFE CYCLE OF GEPHYROCAPSA OCEANICA, WITH REMARKS ON RELATIONSHIPS WITHIN THE NOELERAHBDACEAE AND ISOCHRYSIDACEAE
Ian Probert (1), Jacqueline Fresnel (1), Kees van Lenning (2), Hanno Kinkel (3) & Chantal Billard (1)
1 Laboratoire de Biologie et Biotechnologies Marines, Universite de Caen Basse Normandie, Caen, France
2 Dept. of Marine Biogeochemistry & Toxicology, Nederlands Institut voor Onderzoek der Zee, Texel.
3 Dept. of Marine Biogeochemistry & Toxicology, Nederlands Institut voor Onderzoek der Zee, Texel.
Gephyrocapsa oceanica exhibits certain ultrastructural features which are unusual among the coccolithophorids, but all of these features are identical to observations previously made on Emiliania huxleyi. Observations on the life cycle of G. oceanica, which like E. huxleyi involves alternations between coccolith bearing non-motile cells and scale bearing flagellate cells, are reported. Similarities between the ultrastructure and life cycle of the Noelerahbdaceae and the Isochrysidaceae are discussed. Analysis of lipid and pigment composition of these two families confirms a discrete grouping within the haptophytes, but interesting anomolies are presented. We conclude that G. oceanica is in most ways very similar to E. huxleyi, the main distinguishing characteristic, coccolith morphology, itself showing more or less continuous variation, and hence that generic separation may be questioned.
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