Euastrum crassum Ralfs, 1848
Most likely ID: n.a.
Synonyms: Euastrum crassum var. taturnii, Euastrum crassum f. scrobiculatum
Sampling location: Ibmer Moor (Austria), Schwemm Moor (Austria)
Phylogenetic tree: Euastrum crassum
Diagnosis:
- semi-sells almost trapezoidal or rectangula
- length 140–200 µm, width 75–90 µm
- apical lobe separated by deep incision
- sometimes two lateral lobes per semi-cell
- semi-cells with each 3 basal protuberances
- one central pore in each semi-cell
- deep, linear sinus
- chloroplasts with several, scattered pyrenoids
- cell wall punctate
So far, I have only found Euastrum crassum in the Ibmer Moor (Austria) and in the Schwemm Moor (Austria). In these locations, the species occurs in large numbers in some places.
Euastrum crassum is easily recognizable by its more or less trapezoidal semi-cells. The apical lobe is divided by a deep incision, which is closed at the top. The cell wall is clearly thickened at all protuberances. Each half-cell has three basal protuberances near the isthmus, which can sometimes touch at the cell equator. Approximately in the middle of each semi-cell there is a large pore that is clearly visible (s. fig. 2). Otherwise, the cell wall appears finely granulated due to many smaller pores. The chloroplasts in the semi-cells each contain a few scattered pyrenoids.
Fig. 1 a-b: Euastrum crassum. L = 150 µm. Thwo focal planes of a specimen in brightfield illumination. Obj. 60 X.
Fig. 1 a-b: Euastrum crassum. L = 144 µm. A second specimen with focal plane on the central pores (CP 1, CP 2) of the semi-cells. The middle of the three basal protuberances (BP) is also in focus. Obj. 100 X.