Unarmoured dinoflagellates from Australian waters II.: Genus Gyrodinium (Gymnodiniales, Dinophyceae)

Eighteen species of unarmoured, marine dinoflagellates assignable to Gyrodinium Kofoid et Swezy 1921 were encountered during a survey of the flagellate flora near Melbourne, Australia, 1985-1986. Nine are previously undescribed. Species are described and illustrated by micrographs and drawings of live cells. Four of the new species, marked by (+) below, are phototrophic. The new species are: Gyrodinium acrotrochum (+), G. atractos, G. cladochroma (+), G. guttula, G. heterogrammum, G. impendens (+), G. leptogrammum. G. vesiculosum, G. zeta (+).