Impletosphaeridium erinaceum (Morgenroth, 1966a, p.33-34, pl.8, figs.10-12) Stover and Evitt, 1978, p.178.
Holotype: Morgenroth, 1966a, pl.8, fig.10.
Originally Impletosphaeridium, subsequently (and now) Operculodinium.
Age: Early Eocene.