Baltisphaeridium divergens, (Eisenack, 1954), Downie and Sarjeant, 1963

Now Operculodinium. Originally Hystrichosphaeridium, subsequently Baltisphaeridium (combination not validly published), thirdly Cordosphaeridium, fourthly (and now) Operculodinium.
Combination not validly published since Downie and Sarjeant, 1963 did not fully reference the basionym.

Holotype: Eisenack, 1954, pl.9, fig.14
Age: Early Oligocene