Baltisphaeridium microspinosum, (Eisenack, 1954), Downie, 1959

Now Visbysphaera (an acritarch genus). Originally Hystrichosphaeridium, subsequently Baltisphaeridium, thirdly Lophosphaeridium (an acritarch genus), fourthly (and now) Visbysphaera (an acritarch genus); see also Buedingiisphaeridium (an acritarch genus; combination not validly published).

Holotype: Eisenack, 1954, pl.1, fig.8
Age: Silurian (Late Llandovery)