Alterbidinium pentangulare, Vasilyeva in Andreeva-Grigorovich et al., 2011, p. 44, pl.11, figs.9–10; text-fig.18d ex Williams and Fensome, 2016, p.138.

This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.44) since the holotype citation (pl.11, figs.9–10 and text-fig.18d) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium pentangulare.

Holotype: Andreeva-Grigorovich et al., 2011, pl.11, figs.10; text-fig. 18d, designated by Williams and Fensome (2016, p.138).
Age: Ypresian.