From Fensome et al., 2019:
Caligodinium aceras (Manum and Cookson, 1964, p.27–28, pl.6, figs.9–11) Lentin and Williams, 1973, p.21. Holotype: Manum
and Cookson, 1964, pl.6, fig.9. Originally Kalyptea, subsequently (and now) Caligodinium, thirdly Pareodinia.
Lentin and Williams (1975, p.2148) retained this species in Caligodinium. Taxonomic junior synonym:
Caligodinium amiculum, according to Heilmann-Clausen (1985, p.18) — however, Lentin and Williams (1989,
p.44) retained Caligodinium amiculum. Age: Cenomanian.

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Original description as Kalyptea aceras: [Manum and Cookson, 1964, p.27]:

Description:
Shell oval without horns or appendages, enclosed in a delicate, veil-like covering which extends beyond the shell to varying widths Shell-wall c. 2 µm thick, its inner surface ornamented by a network composed of fairly regular meshes c. 1 µm across. A break present in most examples near one end of the shell is indicative of an apical archeopyle.

Dimensions:
shell 80 x 100 µm, overall 110 x 130 µm.
Range: shell 70-80 x 90-105 µm.