Bachmann (1933)
reported that the species did not exist in the samples collected by E.B. Worthington towards
the end of the 1920s (Worthington, 1930). Interestingly, in modern phytoplankton lists of the
African Great Lakes, A. discoidea is absent. Our findings confirm that this taxon is
morphologically different from A. flos-aquae with regard to the arrangement of the trichomes
within the colonies. Nevertheless, up to now no other diacritical characteristic has been found.
For example, it would be useful to study akinete morphology in A. discoidea filaments,
however, these ontogenic cells have never been found. Hence the issue of whether the two
species should be considered as separate taxa still remains unclear.