Pachysphaeridium brevispinosum (Eisenack, 1931, p.111, pl.5, figs.3–5 ex Eisenack, 1938a, p.12) Ribecai and Tongiorgi, 1999, p.123.

Originally Ovum hispidum subsp. brevispinosum (name not validly published), subsequently Hystrichosphaeridium brevispinosum, thirdly Baltisphaeridium brevispinosum (Acritarch), fourthly Buedingiisphaeridium brevispinosum (combination not validly published, Acritarch), fifthly (and now) Pachysphaeridium brevispinosum.

Holotype: Eisenack, 1931, pl.5, fig.3, as Ovum hispidum subsp. brevispinosum, lost according to Eisenack (1959, p.197).
Neotype: Eisenack, 1959, pl.15, fig.13, designated by Eisenack (1959, p.197), lost according to Ribecai and Tongiorgi (1999, p.124).
New Neotype: Eisenack, 1959, pl.15, fig.16, designated by Ribecai and Tongiorgi (1999, p.124).
Age: Silurian.