I have found Micrasterias thomasiana var. notata in samples from a bog pond near the Warnsdorf spring (Tharandt forest). The specimens were found on the surface of the mud layer and on the walls of the sample container.

Micrasterias thomasiana var. notata can easily be confused with the nominal variety Micrasterias thomasiana and also with Micrasterias denticulata. Micrasterias thomasiana var. notata differs from Micrasterias thomasiana by the three projections at the base of each semi-cell. These are dome-shaped without spines. In Micrasterias thomasiana, however, the lateral projections have each two spines. It is therefore important to focus on the cell surface during the examination. The species Micrasterias denticulata has a similar cell shape to Micrasterias thomasiana var. notata, but the distal ends of the lobes lack spines.