Desmodesmus asymmetricus
(Schröder) Hegewald, 2000
Most likely ID: n.a.
Synonyms: Scenedesmus quadricauda var. asymmetricus, Scenedesmus pseudasymmetricus, Scenedesmus abundans var. asymmetricus, Scenedesmus asymmetricus, Scenedesmus heimii, Scenedesmus jovis, Scenedesmus opoliensis var. aculeolatus, Scendesmus rostrato-spinosus var. kristianisensis
Sampling location: Simmelried
Phylogenetic tree: Desmodesmus asymmetricus
Diagnosis:
- linear coenobia of 2–4 cells
- cells 16–17 µm long, width 3–3.5 µm
- inner cells cylindrical with tapered and rounded ends.
- at the apices of the inner cells with two spines diagonally opposed to each other
- marginal cells slightly convex on contour side
- marginal cells with a curved spine at each apex
- in the equatorial zone of each cell an additional spine on one side of coenobium
- cell wall smooth, without ornamentation
- each cell with one pyrenoid
I have found Desmodesmus asymmetricus so far exclusively in the Simmelried. The species occurs regularly, but never in large numbers. Mostly I find single, isolated specimens. Desmodesmus asymmetricus can be identified by the spines in the equatorial zone of the coenobium (s. fig. 1b) and by the convex shape of the outer cells (s. fig. 1a).
Fig. 1 a-b: Desmodesmus asymmetricus. L = 12 µm (of coenobia). Two focal planes of a slighty squashed specimen. Note the convex contour of the marginal cells (arrow). ES = equatorial spines, DS = diagonally arranged spines of the inner cells. PY = pyrenoid. Obj. 100 X.