Hystrichosphaeridium balticum

"balticum" Eisenack, 1951, p.190, pl.3, figs.10–11.  Holotype: Eisenack, 1951, pl.3, fig.10.  NOW Pachysphaeridium (Appendix A).  Originally Hystrichosphaeridium, subsequently Pulvinosphaeridium (combination not validly published; Appendix A), thirdly Veryhachium (Appendix A), fourthly Goniosphaeridium (Appendix A), fifthly Baltisphaeridium (Appendix A), sixthly Estiastra (Appendix A), seventhly (and now) Pachysphaeridium (Appendix A).  Age: Early Ordovician.

Parent: Hystrichosphaeridium