Isabelidinium bujakii Marheinecke, 1992

Taxonomic senior synonym: Deflandrea (now Isabelidinium) cooksoniae, according to Fensome et al. (2009, p.39).
Contrary to the opinion of Lentin and Williams (1993, p.357), Williams et al. (1998, p.339) considered this name to be validly published.

Holotype: Marheinecke, 1992, pl.18, figs.2-3
Locus typicus: Hemmoor, Lower Saxony, Germany
Stratum typicum: Early Maastrichtian
Translation Marheinecke, 1992: LPP

Original description: Marheinecke, 1992, p. 86-87
Bicavate, peridiniacean cyst. Epiperiblast with small shoulders. Above the lateral angles is the epiperiblast triangular. A short round apical horn, distally blunt, exsists. Hypoperiblast nearly of equal size. Antapex flattened with slightly indicated antapical horns or unequal horns of medium size. Periblast thinwalled, granulate, colourless to weakly coloured. Length/breadth ratio 2:1 or larger. Endoblast subsphaerical, colouless to weakly coloured. Length axis may lie horizontal or vertical. Surface ornamentation of periblast granulate, The endoblast shows no ornamentation or weak granulation. Archaeopyle intercalary 2a/2a, steno-thetraform. Operculum adnat or secate. Cingulum, sulcus or other areation indications not developed.

Affinities:
Marheinecke, 1992, p. 87: I. bujakii differs from other forms in the shape of the epiperiblast and the length/breadth ratio.