Difflugia lebes (Penard, 1893) Penard 1899
Basionym: Difflugia urceolata var. lebes Penard, 1893

Diagnosis: Shell spherical with a neck. Neck sometimes indistinct; aperture large and entire. Shell very fragile, covered with flattened siliceous particles. Collar straight, rarely recurved (= var. elongata Penard). Sometimes more than 100 nuclei.

Dimensions: According to Penard (1902): shell length 360–380 µm, some specimens 400 µm or more. My measurements: 235–239 µm (n = 4).

Ecology: Freshwater; feeding on large diatoms. Occurs in the ooze at the bottom of lakes and ponds.

Geographical distribution: Europe.

Remarks: Although Penard mentions this as a very large species, specimens in one of his stained slides (see below) are not larger than 279 µm. I am not sure whether this is a true species. What is the difference from tests of D. urceolata with a less developed collar

Varieties:

D. lebes sphaerica Gauthier-Lièvre & Thomas, 1958
Shell spherical. The aperture is large and rounded.
Length 270–290 µm, width 270–290 µm, aperture diameter 130–180 µm.

D. lebes masurica Schönborn, 1965
Differs from the typical form by its smaller size.
Length 150–200 µm, width 150–180 µm.