Impletosphaeridium? primordiale W. Wetzel, 1967

Taxonomic senior synonym: Hystrichosphaeridium (now Polygonium) polygonale, according to Eisenack et al. (1973, p.497-498).
Questionable assignment: Wetzel (1967b, p.41).

Holotype: W. Wetzel, 1967, pl.3, fig.18
Age: Ordovician