Hystrichosphaeridium spinosum (White, 1842) Lejeune-Carpentier, 1941

Now Exochosphaeridium?. Originally Xanthidium, subsequently Hystrichosphaeridium, thirdly Baltisphaeridium, fourthly Exochosphaeridium, fifthly (and now) Exochosphaeridium?. See also Cordosphaeridium (combination not validly published).

Holotype: White, 1842, pl.4, fig.6; lost according to Sarjeant (1966b, p.141).
Age: Late Cretaceous