Quadrulella longicollis Taranek, 1882

Diagnosis: Much larger than Q. symmetrica and with straight sides, usually without pronounced lips.

Dimensions: c. 150 µm.

Habitat: Sphagnum and green mosses.

Geographical distribution: Likely cosmopolitan (Kosakyan et al., 2025).

Remarks: The specimens below were collected from the Heelsumse Beek, a clear stream near the city of Arnhem. These shells were the only Arcellinida which were found in a thin layer of sediment in this oligotrophic stream, fed by pure groundwater. The shell length ranges from 69-147 µm. The two smaller ones are Q. symmetrica, the largest three are Q. longicollis. Kosakyan et al (2012) found genetic distances, up to 11%, between Q. symmetrica and Q. longicollis.