OBSERVATIONS ON CULTURED RETICULOFENESTRA PARVULA / A NEW EMILIANIA HUXLEYI MORPHOTYPE?
Ian Probert (1), Jacqueline Fresnel (1), Hanno Kinkel (2), Kees van Lenning (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 Institut de Ciencias del Mar, CSIC, Passeig J. de Borbo, Barcelona, Spain
Several strains of a coccolithophore isolated from the Tasman Sea close to NZ may equally well be identified as Reticulofenestra parvula or Emiliania huxleyi. Within each of these strains considerable variability in coccolith morphology is observed, the distal shield elements of some coccoliths being thick enough to form a solid shield (Reticulofenestra parvula-like), while in other less calcified coccoliths, slitting is observed in the distal shield (Emiliania huxleyi-like). The two types of coccolith are often seen on the same cell, morphological plasticity which seems to be fairly common in the Noelerhbdaceae. The effect of culture conditions on coccolith morphology was examined. The cell ultrastructure and life cycle are described, and the lipid and photosynthetic pigment composition of these strains is compared to those of other members of the Noelerahbdaceae. The biogeography of Reticulofenestra-like coccospheres in present-day oceans is discussed, the most frequent observations being from the Pacific. The morphological plasticity in coccolith structure observed within this family may cause problems for accurate identification and classification, particularly of isolated coccoliths in geological samples.
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