Difflugia brychtai  Stepanek, 1967 (=D. mammillaris)

Diagnosis: Shell pyriform, with the fundus bearing a long, thick spike that is offset from the longitudinal axis, giving the test an irregular appearance. It is covered with large mineral grains, and the pseudostome is round.

Dimensions: Stepanek (1967): Shell length 81 µm; width 46 µm; pseudostome 24 µm, n=1; Opravilova and Stepanek, 1980: Length 120 µm; width 69 µm; pseudostome 28 µm (n=1).

Ecology: Freshwater. Europe.

Remarks: The description of this species is based on a single shell (see Opravilova and Stepanek, 1980). Interestingly, the authors also identified a second shell, markedly different in shape and size and originating from a different location, as belonging to the same species. Given the significant morphological differences between these two shells, it is challenging to conclusively determine whether they belong to the same species. However, I have observed similar variation within populations of D. mammillaris, though only after studying multiple specimens. Both forms of D. brychtai fall within the morphological range of D. mammillaris, and in my opinion, D. brychtai is a junior synonym of D. mammillaris.