Impletosphaeridium panniforme (Gerlach, 1961) Morgenroth, 1966

Originally Baltisphaeridium, subsequently Impletosphaeridium, thirdly Cleistosphaeridium.
Tax. jr. synonym of Hystrichosphaeridium (now Systematophora) placacantha Deflandre and Cookson, 1955, according to Sarjeant, 1984.
Holotype: Gerlach, 1961, pl.28, fig.13
Age: Middle Oligocene