Cell of Micrasterias rotata. Note the gradual widening of the median incision of the apical lobe and the emarginate lobules at the cell margin.

Cell dimensions (L x B): ca 280 x 250 µm



Desmid of the month
June 2005

Micrasterias rotata

M. rotata may be confused with some other Micrasterias species, in particular M. thomasiana and M. fimbriata. From M. thomasiana it differs in the shape of the apical median incision (relatively narrow and clear-cut in M. thomasiana, gradually widening in M. rotata), from M. fimbriata in the shape of the highest-order lobules (spinous-denticulate in M. fimbriata, emarginate in M. rotata).

Although M. rotata holds as one of the commoner Micrasterias species, in the Netherlands its distribution is seriously curtailed due to deterioration of the natural habitat. Today M. rotata is only occasionally encountered in mesotrophic moorland pools, peat pits and fen hollows.

Another cell of Micrasterias rotata
Image © Henk Schulp

Another cell of M. rotata showing two prominent, longitudinal chloroplast ridges in each of the apical lobes as well as many scattered globose pyrenoids.



Spiny zygospore of Micrasterias rotata.

Detail of zygospore showing single spines some of which being hook-shaped at the end.

see also

"The process of asexual reproduction" showing a dividing
Micrasterias rotata