Hystrichosphaeridium hirsutoides var. hamatum
From dinoflaj2
"var. hamatum" Downie, 1958, p.335, pl.16, fig.1; text-figs.2j-k. Holotype: Downie, 1958, pl.16, fig.1. NOW Baltisphaeridium hamatum (Appendix A). Originally Hystrichosphaeridium hirsutoides var. hamatum, subsequently Baltisphaeridium hirsutoides var. hamatum (Appendix A), thirdly Micrhystridium hamatum (Appendix A), fourthly Acanthodiacrodium hamatum (Appendix A), fifthly (and now) Baltisphaeridium hamatum (Appendix A). Age: Early Ordovician. Parent: Hystrichosphaeridium hirsutoides