Diagnosis: Shell a spherical dome where the height of the cap is longer than the radius of the sphere; wall double layered with alveoli in between. Dorsal part usually with some undulations. Shell clearly punctuated, colorless to yellow and brown. Aperture smaller than the diameter of the shell, surrounded by a somewhat broadened rim. Cytoplasm doesn't fill the shell completely, nucleus spherical, with some scattered nucleoli.
Dimensions: My measurements: diameter 51-57 µm (n=10), height 39-42 µm, nucleus 19 µm (n=1).
Ecology: freshwater, in Sphagnum from Das Rotes Wasser, Germany. Not rare.