Impletosphaeridium nanus (Rozen, 1965, p.311, pl.2, figs.7-8; text-fig.21) Islam, 1993, p.86.
Holotype: Rozen, 1965, pl.2, figs.7-8.
Originally Cordosphaeridium microtriainum var. nanus, subsequently Cordosphaeridium microtriainum subsp. nanus, thirdly Cleistosphaeridium? nanus, fourthly (and now) Impletosphaeridium nanus. N.I.A.
Age: Late Eocene.