Alterbidinium nummuliforme, Vasilyeva in Andreeva-Grigorovich et al., 2011, p. 43, pl.11, figs.15–17; text-fig.18c ex Williams et al., herein.

This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.43) since the holotype citation (pl.11, figs.15–17 and text-fig.18c) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium nummuliforme.

Holotype: Andreeva-Grigorovich et al., 2011, pl.11, fig.15; text-fig.18c, designated by Williams and Fensome (2016, p.138).
Age: Thanetian–Ypresian.