Pyxidicula gigantea Decloitre, 1965
Diagnosis: This species is characterized above all by its big size, 360-400 µm in diameter, almost circular in outline. The center is dark yellow and surrounded by a portion of a clear yellow tint which, again, is surrounded by a quite transparent portion. The dark yellow portion corresponds to an endoplasm, the transparent portion to an ectoplasm. Nucleus nearly central, 70 µm in diameter, with two large nucleoli. Membrane consists of very fine areoles, which are irregularly hexagonal. Seen from above, the pseudostome almost marks the limit of the ectoplasm. The central part of the test seems to be without areoles. Where the membrane is naked, it is quite transparent, without any signs of colour.
Dimensions: Length 360-400 µm.
Ecology: Freshwater, oligotrophic. Iceland, 1933.