Sentusidinium pilosum "forma ?nanus" Wetzel, 1933b, p.43, pl.4, fig.23; text-fig.13 ex Lentin and Williams, 1985, p.322. Emendation: Sarjeant, 1985b, p.145, as Prolixosphaeridium nanus.

NOW Prolixosphaeridium? nanus. Originally Hystrichosphaera pilosa forma nanus (name not validly published), subsequently Sentusidinium pilosum? subsp. nanus, thirdly Prolixosphaeridium nanus, fourthly (and now) Prolixosphaeridium? nanus. Questionable assignment: Lentin and Williams (1985, p.322). The name Hystrichosphaera pilosa forma nanus was not validly published in Wetzel (1933b) since the species combination Hystrichosphaera pilosa was not validly published. N.I.A.

Holotype: Wetzel, 1933b, pl.4, fig.23; Sarjeant, 1985b, pl.2, figs.6–7.
Age: Late Cretaceous.