Arcella brasiliensis Cunha, 1913
Diagnosis: Shell circular in apertural view, hemispherical in lateral view, with a distinct marginal rim. Dorsal surface provided with depressions, promoting an undulate aspect. Aperture circular, central, invaginated, delimited by a curled lip.
Dimensions: shell diameter: c. 80 µm.
Ecology: between aquatic mosses and waterplants, South-America.