From Fensome et al., 2019:
Cleistosphaeridium tenuifilum Cookson and Eisenack, 1982, p.40, pl.8, fig.14. Holotype: Cookson and Eisenack, 1982, pl.8, fig.14. NOW Impletosphaeridium?. Originally Cleistosphaeridium, subsequently (and now) Impletosphaeridium?. Age: Paleocene.

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