From Fensome et al., 2019:
Sentusidinium microcystum (Bujak in Bujak et al., 1980, p.88,90, pl.22, figs.2–5) Islam, 1993, p.88. Holotype: Bujak et al., 1980,
pl.22, figs.2–3; Fauconnier and Masure, 2004, pl.64, figs.4–5. Originally Tenua Eisenack, subsequently
Cleistosphaeridium, thirdly (and now) Sentusidinium, fourthly Pilosidinium. Wood et al. (2016, p.85) retained this
species in Sentusidinium. Age: Middle Eocene (see Aubry, 1986).

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Original diagnosis: Bujak in Bujak et al., 1980, p.88-89: Tenua microcysta
Autocyst ovoidal, sometimes with two weakly developed antapical lobes. Autophragm smooth to chagrinate with abundant processes. The processes are nontabular and are of constant length on a specimen, but vary in length intraspecifically. The processes are mostly expanded proximally, hollow, and are distally capitate or bifid. Occasional processes are solid or simple. The archaeopyle is apical, tetratabular, and has well-developed accessory archaeopyle sutures between the precingular paraplates. The operculum is detached.
Dimensions. Autocyst length (without operculum) = 28-36 µm, breadth = 24-34 µm. Process length is up to 6 µm.