Quadrulella variabilis Kosakyan et al., 2016
Description. Test ovoid or pyriform, with a rounded posterior end, laterally compressed towards the pseudostome, very similar to that in Q. symmetrica, sometimes with an elongated neck. Test colorless, composed of square plates, regularly arranged in rows. The plates are smaller near the aperture (3-4 µm), then gradually become larger (up to 7-9 µm ) toward the posterior end of the test. Aperture often curved and bordered by a thin organic lip.
Dimensions: Length: 66-69 (96) µm, breadth: 35-40.5 (45) µm . Aperture 17- 18.5 µm wide (n=7). My measurements: L 71 µm, aperture 17 µm wide, plates 3.4-9.4 µm.
Ecology: Sphagnum mosses, Switzerland.
Remarks: The species has members with a variable neck length. The records from one location suggest rather a species complex than distinct intraspecific diversity.