Apteodinium monacanthum

?monacanthum (Deflandre, 1936b, p.176–177, pl.5, fig.10 ex Sarjeant, 1967b, p.252) Helenes, 1984, p.134.  Holotype: Deflandre, 1935, pl.6, fig.1; Deflandre, 1936b, pl.5, fig.10; lost according to Jan du Chêne et al. (1986a, p.48).  Originally Palaeoperidinium (name not validly published), subsequently Gonyaulacysta, thirdly Millioudodinium, fourthly Apteodinium, fifthly (and now) Apteodinium?.  Questionable assignment: Jan du Chêne et al. (1986a, p.48), as a problematic species.  Jan du Chêne et al. (1986a, p.48) recommended that the name be restricted to the holotype.  The name Palaeoperidinium monacanthum was not validly published in Deflandre (1935) since the generic name Palaeoperidinium was not validly published until 1967.  Williams et al. (1998, p.49) accepted Sarjeant's (1967b) indirect reference to Deflandre (1935) as indication of a type (I.C.N. Article 40.1).  Age: Late Cretaceous.

Parent: Apteodinium