Phylum: Charophyta   Family: Desmidiaceae

Staurastrum crenulatum sensu G.S. West 1899

First described and illustrated by Nägeli (1849: 129, pl. 8: B) as Phycastrum crenulatum. It was later moved by Delponte (1877: 68, pl. 12: 1-11) to Staurastrum. West’s concept of this species deviated markedly from Nägeli’s original and would perhaps be better renamed. It has some features in common with S. paradoxum but that species, above all else, is noted for its large spines at the ends of the processes.
Single cell dimensions: L: 18.6 µm; B: 29.9 µm; Is: 7.1 µm; L/B: 0.6.
Recorded in Europe as widely distributed and locally very common in eutrophic waters. It is proving scarce in the Outer Hebrides.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.