Baltisphaeridium brevispinosum ssp. callosum, (Sannemann, 1955), Fensome et al., 1990

Originally Hystrichosphaeridium brevispinosum ssp. callosum, subsequently (and now) Baltisphaeridium brevispinosum ssp. callosum; see also Buedingiisphaeridium brevispinosum ssp. callosum (an acritarch subspecies; combination not validly published).
Kjellstroem, 1971 listed this subspecies questionably in his synonymy for Baltisphaeridium brevispinosum. The name Baltisphaeridium brevispinosum ssp. callosum was not validly published by Downie and Sarjeant, 1963 since these authors did not fully reference the basionym, nor was it validated by Eisenack et al., 1973, since these authors did not give a clear indication of taxonomic rank. Elsewhere in the same publication, Eisenack et al., 1973 implied that this taxon should be excluded from the species Baltisphaeridium brevispinosum.

Holotype: Sannemann, 1955, pl.4, fig.3
Age: Devonian (Late Givetian)