Baltisphaeridium nanus, (Deflandre, 1945a, p.62–63, pl.1, figs.5–7), Stockmans and Willière, 1962a, p.54–55.

NOW Polygonium nanus (Appendix A). Originally Hystrichosphaeridium brevispinosum var. nanus, subsequently Baltisphaeridium brevispinosum var. nanus (combination not validly published, Appendix A), thirdly Baltisphaeridium nanus, fourthly Micrhystridium nanus (Appendix A), fifthly (and now) Polygonium nanus (Appendix A), sixthly Solisphaeridium nanus (Appendix A). Taxonomic junior synonym (at specific rank): Baltisphaeridium brevispinosum var. wenlockense (subsequently Salopidium wenlockense) Downie, 1959, an acritarch taxon, according to Lister (1970, p.54). N.I.A.

Holotype: Deflandre, 1945a, pl.1, figs.5–6.
Age: Silurian.