Assulina collaris Kufferath, 1932

Diagnosis: Shell elliptical in broad view, with a short neck that is smooth rather than crenulated or scaly. Shell brown‑violet, covered with overlapping elliptical scales arranged from bottom to top and aligned along crossed diagonal lines. In lateral view, the shell is flattened, with one face nearly flat and the other slightly convex.

Dimensions: Kufferath (1932): shell length 52–52 µm; width 38 µm; neck 12 µm wide and 3 µm high.

Ecology: On the bark of a cacao tree.

Distribution: Barumbu, north of Kinshasa, Democratic Republic of the Congo (Kufferath, 1932); southern Sweden (Siemensma, 2026, Arcella.nl).