Baltisphaeridium oligacanthum ssp. complanatum, (W. Wetzel, 1952), Downie and Sarjeant, 1965

Now Solisphaeridium stimuliferum ssp. complanatum (an acritarch subspecies). Originally Hystrichosphaeridium oligacanthum ssp. complanatum, subsequently Baltisphaeridium oligacanthum ssp. complanatum, thirdly Cleistosphaeridium? oligacanthum ssp. complanatum, fourthly (and now) Solisphaeridium stimuliferum ssp. complanatum (an acritarch subspecies).

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