Cleistosphaeridium uncinispinosum, (de Coninck, 1969, p.32-33, pl.9, figs.6-8), Islam, 1983b, p.342.

Originally Cordosphaeridium, subsequently Cordosphaeridium?, thirdly Cleistosphaeridium, fourthly (and now) Operculodinium.

Holotype: de Coninck, 1969, pl.9, figs.6-8.
Age: Early Eocene.