Polysphaeridium belgicum Sarjeant, 1969, p.15. Holotype: Pastiels, 1948, pl.3, fig.16, as Hystrichosphaeridium fluctuans, lost according to Sarjeant (1986, p.18). Originally (and now) Polysphaeridium, subsequently Polysphaeridium?, thirdly Dapsilidinium?. Questionable assignment: Stover and Evitt (1978, p.76) — however, Sarjeant (1986, p.18) retained this species in Polysphaeridium without question. Sarjeant (1969, p.15) based this species on material described by Pastiels (1948, p.40, pl.3, fig.16) as Hystrichosphaeridium fluctuans. Age: early Eocene.