Micrhystridium diploporum (Eisenack, 1951) Downie and Sarjeant, 1963

Name not validly published since Downie and Sarjeant, 1963 did not fully reference the basionym and did not intend to create this combination.
Now Baltisphaeridium (an acritarch genus). Originally Hystrichosphaeridium, subsequently Micrhystridium, thirdly (and now) Baltisphaeridium (an acritarch genus.
Holotype: Eisenack, 1951, pl.2, fig.6
Age: Ordovician (based on material from an erratic)