From Fensome et al., 2019:
Membranilarnacia? minuta de Coninck, 1969, p.43, pl.12, figs.13–14. Holotype: de Coninck, 1969, pl.12, figs.13–14; Fauconnier and Masure, 2004, pl.54, figs.8–9. Originally Membranilarnacia, subsequently (and now) Membranilarnacia?. Questionable assignment: Stover and Evitt (1978, p.64). Age: Early Eocene.

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Original description (de Conink, 1969):
Membranilarnacia minuta nov. sp. (Pl. XII, fig. 13 et 14.)
Holotype: Kallo -374, 5 m. Préparation 1; coord. 40,3-96,3.

Diagnosis: The organism is small and bears solid, straight processes that measure about one-third the shell diameter. Their distal end, vaguely flared (or bifurcated?), supports a membrane into which these possible bifurcations are inserted. I did not observe any archaeopyles. The organism's characteristics clearly differentiate it from other species of the genus.
Dimensions of the central body: about 12 µm.
Height of processes: 2 µm to 3 µm.
Total wingspan: about 20 µm by 22 µm.