Membranosphaera maastrichtica Samoilovitch in Samoilovitch and Mtchedlishvili, 1961

See also Elytrocysta druggii Stover and Evitt, 1978
Holotype: Samoilovitch and Mtchedlishvili, 1961, pl.83, figs.1a-d
Age: Santonian-Late Eocene