Description of Gonyaulax spinifera

G. spinifera cells are slightly longer than broad. The epictheca has convex sides and a small epical horn. The hypotheca has 2-4 antapical spines. The sulcus extends almost the whole length of the cell. The cingulum is deeply excavated and displaced by 2 or more widths. G. spinifera is sometimes confused with Gonyaulax digitale.  It is likely that Gonyaulax spinifera is actually a species complex rather than a single species.