Image © Wim van Egmond
Just like in Micrasterias truncata the lateral semicell lobes in M. jenneri are only twice divided (to lobules of the second order) and the apical lobe is very short and broad. Most relevant discriminating characteristic of Micrasterias jenneri (as compared to M. truncata) is the shallow but well-marked, median incision in the apical lobe. In western Europe, the ecological demands of Micrasterias jenneri are comparable with those of Xanthidium armatum and Cosmarium ralfsii, i.e., acidic, boggy pools with a slight input of minerals from the (often loamy) subsoil. Nowadays, Micrasterias jenneri in the Netherlands is a rare species, particularly known from a few moorland pools in the province of Drenthe.
Image © Henk Schulp
Cell of Micrasterias jenneri with littered chloroplast: a familiar (almost distinctive) appearance of this species.