Euastrum rhomboidale
(Ducellier) Coesel & Meesters, 2023
Most likely ID: n.a.
Synonym: Euastrum ansatum var. rhomboidale
Sampling location: Lauchsee Moor (Austria)
Phylogenetic tree: Euastrum rhomboidale
Diagnosis:
- semi-cells rhompoid, lateral margins straight
- length 70–108 µm, width 40–50 µm
- apices flat
- apical lobe separated by deep incision
- semi-cells with each 5 inconspicuous protuberances
- cell wall with fine pores
- sinus deep, linear
So far, I have only found Euastrum rhomboidale in the Lauchsee Moor in Austria. Until 2023, Euastrum rhomboidale was considered a variant of Euastrum ansatum and then elevated to its own species by Coesel & Meesters.
A key feature of Euastrum rhomboidale are the straight, lateral margins of the semi-cells. They are not concavely shaped like in the similar species Euastrum ansatum.
Fig. 1 a-b: Euastrum rhomboidale. L = 105 µm. Two focal planes of a specimen in DIC. Note the small pores covering the cell wall (b). Obj. 100 X.
Fig. 2 a-b: Euastrum rhomboidale. L = 105 µm. The same specimen as shown in fig. 1 a-b in brightfield illumination. Obj. 100 X.