Operculodinium alsium Matsuoka and Bujak, 1988, p.64-65, pl.8, figs.7,8a-b,9.
TYPE: Holotype: Matsuoka and Bujak, 1988, pl.8, figs.8a-b; Head, 1994b, pl.8, figs.6-9.
AGE: Late Miocene.