Pyxidicula invisitata Awerinzew, 1906
Diagnosis: shell patelliform, colorless to brown, with distinct punctuation; aperture round, bordered by a narrow hollow rim with areolated structure; contractile vacuole single; pseudopodia unknown; vesicular nucleus with central nucleolus.
Dimensions: Awerinzew (1906): 40-50 µm; Cash: diameter 25-50 µm; my measurements 33-67 µm.
Ecology: Sphagnum. I found this species in Tirol, Austria.
Remarks: All photomicrographs are taken from material kindly supplied to me by Angie Opitz in Tirol, Austria.