Cleistosphaeridium oligacanthum ssp. complanatum, (W. Wetzel, 1952), Lentin and Williams, 1973

Now Solisphaeridium stimuliferum ssp. complanatum. Originally Hystrichosphaeridium oligacanthum ssp. complanatum, subsequently Baltisphaeridium oligacanthum ssp. complanatum, thirdly Cleistosphaeridium? oligacanthum ssp. complanatum, fourthly (and now) Solisphaeridium stimuliferum ssp. complanatum.
According to Sarjeant, 1984, Solisphaeridium stimuliferum ssp. complanatum is an acritarch.

Holotype: W. Wetzel, 1952, pl.A, figs.11a-b; Sarjeant, 1984, pl.4, fig.6; text-fig.13
Age: Paleocene