Achomosphaera? operculata, Sah et al., 1970, p. 144, pl.1, figs.1–2

NOW Operculodinium. Originally Achomosphaera, subsequently Achomosphaera?, thirdly (and now) Operculodinium. Questionable assignment: Stover and Evitt (1978, p.139).

Holotype: Sah et al., 1970, pl.1, fig.1
Age: Late Cretaceous.