Gymnodinium aureolum (Hulburt) Hansen

(Figures 11–14)

Motile cells were yellow-brown in colour and were spherical in outline with a flattened antapex and slight dorsoventral flattening (Figures 11–13). Cells were 30–38 µm long and 25–30 µm wide. The cingulum surrounded the middle of the cell with a slight offset (Figures 11 and 12). The nucleus was centrally placed (Figure 12). Divided cells were occasionally seen as duplets (Figure 14). Cells matched the description given for this species in Hansen et al. (2000). Two strains isolated from Caspian Sea material were successfully sequenced and are placed in the tree alongside strains of Gymnodinium aureolum from South Korea and New Zealand (Figure 32).