From Fensome et al., 2019:
Apteodinium frontierense (Burgess, 1971, p.81, pl.1, figs.6,9; text-fig.13) Stover and Evitt, 1978, p.142. Holotype: Burgess, 1971, pl.1, fig.9; Jan du Chêne et al., 1986a, pl.15, figs.1–6. Originally Coniferatium, subsequently (and now)
Apteodinium. Age: Albian–early Cenomanian.

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Original description as Coniferatum frontierense: [Burgess, 1971, p. 81]:

Description:
Test dorsoventrally flattened, rounded polygonal in outline. A prominent girdle divides the epitheca from the hypotheca. The sculpture consists of a fine to coarse reticulum, being coarsest in the apical, antapical, and girdle areas. The outer reticulate wall is in contact with the capsule except at the poles.
Precingular archeopyle is always present as a triangular- to arch-shaped opening.
The epitheca terminates in a rounded knoblike reticulate mass of spongy tissue.

Dimensions:
Holotype Range
Length 57.6 µm 53-63 µm
Breadth 56.0 µm 50-72 µm