Baltisphaeridium hirsutoides var. hamatum, (Downie, 1958), Downie and Sarjeant, 1965

Now Baltisphaeridium hamatum (an acritarch species). Originally Hystrichosphaeridium hirsutoides var. hamatum, subsequently Baltisphaeridium hirsutoides var. hamatum, thirdly Micrhystridium hamatum (an acritarch species), fourthly Acanthodiacrodium hamatum (an acritarch species), fifthly (and now) Baltisphaeridium hamatum (an acritarch species).

Holotype: Downie, 1958, pl.16, fig.1
Age: Early Ordovician