From Fensome et al., 2019:
Cleistosphaeridium echinoides (Maier, 1959, p.318–319, pl.32, figs.5–6) Davey et al., 1969, p.15. Holotype: Maier, 1959, pl.32, fig.6. Originally Hystrichosphaeridium, subsequently Baltisphaeridium (Appendix A), thirdly Cleistosphaeridium. Taxonomic senior synonym: Xanthidium (as Spiniferites) ramosum, according to Sarjeant (1983, p.91–92). This combination was not validly published in Davey et al. (1966, p.170), since these authors did not fully reference the basionym. Age: middle Oligocene–Middle Miocene.

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Original description as Hystrichosphaeridium echinoides: [Maier, 1959, p.318]: (Translation: LPP):

Diagnosis:
A species of the genus Hystrichosphaeridium with following characteristics: capsule oval-pear-shaped with numerous thin, simple processes.

Description:
Ovale capsule with ornamented membrane. All processes of equal length and blunt ends. Capsule densely covered with spines.

Dimensions:
Diameter 90-107 µm (70-80 µm); 2 specimens.