Cryptodifflugia sacculus Penard, 1902

Diagnosis: (Penard, 1902) Shell elongated, uncompressed, pyriform, with a very wide neck, slightly constricted at the back and widened at the aperture; the latter, when seen from three-quarters or from the front, appears to be surrounded by a collar, which however is only an impression produced on the eye by the widening of the neck. The general form is in short similar to that of Difflugia capreolata, or Difflugia rubescens. The shell wall is organic, transparent, of a yellow which, depending on the age, varies from an almost hyaline shade to golden brown (very rare). On this chitinous membrane are then always stuck foreign particles, more or less numerous, siliceous amorphous fragments, small stones, and very frequently diatoms, which although very recognizable can be of a size quite small not to exceed 5 μm.

Dimensions: Penard (1902): Shell length 17-(20-23)-26 µm. My measurements: 14-25 µm.

Habitat: Freshwater. In sphagnum and peat bogs, but also in other water types; locally not rare.