Hystrichosphaeridium hirsutoides Eisenack, 1951, p.189–190, pl.3, fig.8.

NOW Baltisphaeridium (Acritarch). Originally Hystrichosphaeridium, subsequently (and now) Baltisphaeridium (Acritarch).

Holotype: Eisenack, 1951, pl.5, fig.19, as "Ovum hispidum cf. hirsutum Ehrenb.", lost according to Eisenack et al. (1973, p.125).
Neotype: Eisenack, 1951, pl.3, fig.8, designated by Eisenack et al. (1973, p.125).
Age: Late Ordovician.