Amongst the dinoflagellates, the heterotrophic unarmoured species are the group that has received less attention. The species Gyrodinium postmaculatum, G. rubricaudatum and the genus Pavillardia remain unreported since the original description in 1921. During on-board observations of living plankton in the Agulhas Current in the continental shelf off eastern South Africa, we observed individuals that fit with the description of Pavillardia, G. postmaculatum and G. rubricaudatum, and other intermediate forms. The posterior extension of Pavillardia tentaculifera was not movable, it detached and the cell remained viable. The diagnoses of G. postmaculatum and G. rubricaudatum were based on red colouration, but this feature was highly variable. Pavillardia devoid of the posterior extension is indistinguishable from G. postmaculatum. There are no significant differences in the morphology among Pavillardia tentaculifera, G. postmaculatum, and G. rubricaudatum. Pavillardia is considered a synonym of Gyrodinium, and the name G. postmaculatum is proposed for these three species.