Assulina seminulum  (Ehrenberg, 1848)

Diagnosis: Young shells yellowish, older ones light to dark brown; ovoid, compressed, biconvex in cross‑section, with overlapping oval scales. Aperture narrow‑oval, more or less crenulate, with an organic margin. Nucleus vesicular; filopodia present.

Dimensions: Length 60–150 µm (various authors, summarized in Hoogenraad & De Groot, 1940).
Todorov and Bankov (2019): Length 65–91 µm, shell-plates 9–10 µm long.

Remarks: Lüftenegger et al. (2009) note that A. seminulum and A. muscorum can be separated only by size, with A. seminulum being approximately 1.5× larger than A. muscorum (Hoogenraad & De Groot, 1937). Todorov and Bankov (2019) note that Assulina muscorum differs from A. seminulum by the shape en size of the shell and by the twice smaller shell plates.