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

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

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

Habitat: Freshwater, feeding on large diatoms. In the ooze at the bottom of lakes and ponds.

Geographical distribution: Europe.

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

Varieties:

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

D. lebes masurica Schönborn, 1965
It differs from the typical form of small size.
Length 150–200 µm, width 150–180 µm.