PYCNOCOCCUS PROVASOLII GEN. ET SP. NOV., A COCCOID PRASINOXANTHIN‐CONTAINING PHYTOPLANKTER FROM THE WESTERN NORTH ATLANTIC AND GULF OF MEXICO 1

• Published in: Journal of Phycology
• Main Authors: Guillard, Robert R. L., Keller, Maureen D., O'Kelly, Charles J., Floyd, Gary L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1991
• Subjects: North Atlantic
• Online Access: http://dx.doi.org/10.1111/j.0022-3646.1991.00039.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.0022-3646.1991.00039.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.0022-3646.1991.00039.x

ABSTRACT The new genus Pycnococcus Guillard is based on several clones from the western North Atlantic and Gulf of Mexico. The type and only described species, Pycnococcus provasolii Guillard, sp. nov., is typified by clone Ω 48‐23 from the North Atlantic. Cells of Pycnococcus provasolii are solitary, spherical, 1.5–4.0 μm in diameter, have a resistant cell wall lacking sporopollenin, and have the ultrastructural characteristics of green algae. With the light microscope they are scarcely distinguishable from cells of other coccoid planktonic organisms. In pigmentation P. provasolii resembles Micromonas pusilla, Mantoniella squamata , and Mamiella gilva in having chl a , much chl b , Mg 2,4‐divinylphaeoporphyrin a 5 monomethyl ester (presumably), and prasinoxanthin as a major xanthophyll. The pyrenoid of P. provasolii has a cytoplasmic channel, which is unique among species closely related to it. Flagellates, occurring rarely in culture, are similar to but distinguishable from known Pedinomonas species by size and shape. Pycnococcus provasolii is referred to the new family Pycnococcaceae Guillard, in the order Mamiellales of the class Micromonadophyceae (Chlorophyta). Clones of Pycnococcus provasolii are oceanic in nutritional characteristics, require only vitamin B 12 in culture, and are well adapted to growth under blue or blue‐violet light of low intensity.