Description of Arcella gibbosa
provided by BioPedia
The test is brown, circular and is domed or hemispherical in lateral view. The apertural surface and the basal collar are smooth, but the aboral hemisphere has a series of regular depressions. The shell surface may be smooth or irregular and has numerous small pores. The aperture is invaginated, circular and has a distinct rim or lip. Diameter of test 70-125 microns, height 49-74 microns and diameter of aperture 19-32 microns.
