Phylum: Charophyta Family: Desmidiaceae
Staurastrum arcuatum C.F.O. Nordstedt 1873
Coesel & Meesters (2013) describe the semicells as bowl-shaped with relatively long processes. However, the cell-shape is quite variable in the Outer Hebrides, especially the basal part of the semicell, which can have some angularity. The processes comprise two forked, quite long spines, usually with a short, solid base. Occasionally, just one spine is present.
Overall cell dimensions: L: 34-40 µm; B: 32-41 µm; Is: 8.5-11.3 µm; L/B: 0.90-0.98.
Infrequently recorded in mesotrophic waters that are slightly alkaline, such as loch margins.
References:
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Van Westen, M.C. (2024). Sieralgen in Drenthe.
West, W., West, G.S. & Carter, N. (1923). A Monograph of the British Desmidiaceae, Volume 5.