Arcella discoides var. scutelliformis Playfair, 1918
Diagnosis: Test relatively higher than the type, with nicely rounded sides in cross-section. Contour regular, pseudostome circular, relatively large, sometimes with a ring of fine pores. Dorsal side rounded, without undulations. Pseudostomal invagination about half the height of the shell, without pseudosomal tube.
Dimensions: Playfair (1918): diameter 44-95 µm; height 15-25 µm; pseudostome diameter 14-34 µm. Deflandre (1928): 61-82 µm; height 18-26 µm; pseudostome 17-28 µm.
Ecology: Sphagnum, submerged mosses.