Genus Assulina Greef, 1888
Diagnosis: Shell usually brown, ovoid, compressed, biconvex in cross-section, with overlapping elliptical scales; aperture narrow oval, more or less crenulate with organic margin; nucleus vesicular, filopodia.
Remarks: Five species have been described so far, but they are hard to distinguish from each other light microscopically. It’s questionable if they represent separate species. The original descriptions are inadequate.
- A. muscorum (small, c. 45 µm long)
- A. seminulum (medium sized, c. 85 µm long)
- A. scandinavica (large, c. 100 µm long)
- A. quadratum
- A. minor
- A. collaris