Remarks: Molecular analysis done by Neustupa et al. 2011 revealed that different strains formerly identified as Micrasterias fimbriata Ralfs fell apart in two clades. Close examination revealed that the two clades could also be separated on basis of their morphological characteristics. The clade they called the B-lineage, with spikelike spines, resembles the original description of Ralf. The other taxon, the A-lineage has more finger-shaped spines and although it was noticed by earlier authors, they never recognized it as a separate taxon. It seems that all specimen known from North America belong to M. compereana, the ones from North and East Europe belong to the M. fimbriata, while in West Europe both taxa occur.