Cryptodifflugia pusilla  Playfair, 1917

Diagnosis: Shell minute, subquadrate, as broad as high, with a broadly rounded fundus; sides straight and almost parallel; base the full width of the shell or nearly so. Cross‑section circular. Membrane smooth, thick, chitinous, structureless, without xenosomes.

Dimensions: Playfair (1917): shell diameter 10 µm.
Own measurements: diameter 11–13 µm.
Odenwald sample: diameter 7.9–9.0 µm.

Ecology: Freshwater.

Distribution: Australia; Europe.

Remarks: Several populations observed. The species does not appear to be rare, but specimens consistently contained some xenosomes incorporated into the shell. This suggests that multiple species may be involved.