From Fensome et al., 2019:
Deflandrea arcuata ssp. oporiensis (Grigorovich, 1971, p.92, pl.1, fig.5) Lentin and Williams, 1977b, p.40. Holotype: Grigorovich, 1971, pl.1, fig.5. Originally Deflandrea arcuata forma oporiensis, subsequently (and now) Deflandrea arcuata subsp. oporiensis. Age: Eocene.

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Original description: [Grigorovich, 1971] (translated from Russian):

Holotype. IHGG IU AN UkrSSR, specimen 514-XI; Middle Eocene (Orava Formation); Opor River.

Diagnosis. The theca is pentagonal with convex lateral sides. The epitheca is triangular with a small apical projection. The hypotheca has straight lateral sides with two small antalical projections connected by a slightly concave septum. The internal body is elliptical, adjacent to the theca walls on the epitheca. The transverse groove is absent; sometimes, in its place, small projections are observed on the sides of the theca. The pilometa is large and elliptical.

Holotype dimensions in microns. Theca length is 95, width 93.
Locality and material. Outcrop along the Opor River, Skole village; Middle Eocene, Orava Formation; 10 specimens.