orphology:
Spherical to oval cells densely arranged in rows forming flat and rectangular colonies in mucilage not extending outside a colony’s margins. No distinct sheath around individual cells.
Identical base pair sequences of 16S rDNA in three described species (M. glauca, M. punctata and M. elegans) indicate that, while there is morphological variability in natural populations, the three species should be combined into a single description and name. Further, natural populations kept in culture changed to the point that based on their morphology they would be assigned to different species, or even genera (Palinska et al. 1996).
The precautionary tale is that morphological plasticity and taxonomy based on it can be misleading, especially in the absence of base pair sequences.