Planocarina spumosa (Awerintzew, 1906)

Diagnosis: Shell compressed, with a flat keel, usually starting a little above the middle of the test and covering the entire fundus. In profile, the test has a narrow ovoid shape with a pointed fundus. Shell composed of scattered large ovoid to elongated plates likely obtained from euglyphid testate amoeba prey, with test cement composed of smaller granular elements filling the open spaces between larger plates. The scattered larger test plates give it a somewhat frothy appearance (hence the name). Small cavities ca, 1–15 μm in diameter. Pseudostome ovoid in frontal view, surrounded with an organic rim.

Dimensions: According to Awerinzew (1906): Shell length 275–—295 μm; width 205–—210 μm; aperture 50–—60 μm.

Habitat: Sphagnum vegetation.

Geographical distribution: Russia.

References: Kosakyan, A., Meisterfeld, R., Lara, E., Duckert, C., Mitchell, E., 2025. A taxonomic monograph of hyalospheniid testate amoebae. Amoebozoa: Arcellinida: Hyalospheniformes, Mémoire XIV. Éditions Alphil-Presses universitaires suisses, Neuchâtel.