Difflugia lemani Blanc, 1892
Syn.: Difflugia viscidicula Penard, 1902 pars
Diagnosis: shell elongated oblong, not compressed, resembling an acorn, without distinct neck. Nucleus large, with a distinct membrane and filled with a large number of nucleoli, rounded or amorphous, but mostly flattened.
Dimensions: Blanc (1892): 180-310 µm; Penard (1902): 180-260 µm; my measurements length: 183-211 µm.
Ecology: fresh water; Switserland; Tirol, Austria, the Netherlands (Naardermeer and several other locations).
Remarks: Penard described this species in 1902 as D. viscidicula, but in 1905 he wrote that he had made a mistake by which he thought that D. lemani was a much smaller species. He noticed erroneously 31-80 µm, instead of 180-310 µm, as given by Blanc. However, his figure 3, see below, is quite different from the other two tests. It has a distinct neck and is much more elongated. I consider this as a different species with the name D. viscidula.
Penard describes the shape as that of an acorn.