Euglypha rotunda (Ehrenberg, 1845)
Diagnosis: shell ovoid, more or less compressed, varying in transverse section from circular to oval as it tapers from the mid-body region to the aboral region; shell composed of approximately on hundred and twenty, oval, shell-plates; aperture circular and surrounded by eight to fourteen evenly spaced apertural-plates; each apertural-plate is ovoid, thickened at the denticulate margin and carries a large median tooth which is bordered by two or three smaller teeth; nucleus with one central nucleolus; two contractile vacuoles. All parameters show a rather great variability, especially the size of the idiosomes and the diameter of the aperture.
Dimensions: literature 50-60 µm.
Ecology: Sphagnum and other mosses, also in sediments.
Remarks: This is a small Euglypha species which can be confused with Euglypha laevis. Probably this is a species complex.
In both cultured and wild animals variation appears to be restricted to the occasional large individual, usually having double the normal complement of shell and apertural-plates. (Hedley & Ogden, 1973).