Micrhystridium claviculorum (Deflandre, 1939a, p.191–192, pl.10, fig.4) Sarjeant and Stancliffe, 1994, p.16. Emendation: Sarjeant, 1968, p.223, as Solisphaeridium claviculorum.

Originally Hystrichosphaeridium, subsequently Baltisphaeridium (Acritarch), thirdly Solisphaeridium (Acritarch), fourthly (and now) Micrhystridium.

Holotype: Deflandre, 1939a, pl.10, fig.4.
Age: Late Jurassic.