(1)–2–4 longitudinal, continuos ridges per cell (sometimes absent)
inner and outer cells with short teeth at the apices
margins of the outer cells smooth
one pyrenoid per cell
I have found Desmodesmus brasiliensis in the plankton of Lake Constance in July 1994. The main characteristics of Desmodesmus brasiliensis are the short teeth at the apices (s. fig. 1 a) and the continuous ridges at the sides of the cells (s. fig. 1 b).
The very similar species Desmodesmus lefevrei (synonym = Scenedesmus lefevrei) can be distinguished from Desmodesmus brasiliensis by a fringe of small teeth at the margins of the outer cells (s. Michael Plewka-Freshwater life-Scenedesmus lefevrei).
Fig. 1 a-b:Desmodesmus brasiliensis. L = 19 µm (of coenobium). Two focal planes of a coenobium of 4 cells. Note the short teeth at the apices of the cells (a) and the continuous ridges on the sides of the cells (b). Obj. 100 X.