Scriniodinium dictyotum subsp. dictyotum. Autonym. Holotype: Cookson and Eisenack, 1960b, pl.37, fig.9; Jan du Chêne et al., 1986a, pl.5, fig.1; pl.7, fig.6. Originally (and now) Scriniodinium dictyotum subsp. dictyotum, subsequently Scriniocassis dictyota subsp. dictyota, thirdly Aldorfia dictyota subsp. dictyota.

Original description: Cookson and Eisenack, 1960, p. 248: Scriniodinium dictyotum
Shell flat, oval, divided by a +/- distinct and relatively broad girdle into an epitheca and hypotheca of approximately equal size; epitheca prolonged into a broadly based, short, blunt apical projection. Capsule oval with a short apical prominence. The wall of the capsule bears numerous thin perpendicular ledges which form a small-meshed supporting reticulum for the thin outer membrane. The meshes of the reticulum vary considerably in size and are usually widest towards the periphery. The pylome is broadly hoof-shaped and reaches the girdle.
Dimensions: holotype--109 µm long, 95 µm broad, capsule 95X83 µm.