Phylum: Charophyta Family: Desmidiaceae
Staurastrum pentasterias R. Grönblad 1963
First described and illustrated by Grönblad (1963: 30, pl. 5: 35) who gives very precise measurements suggesting just one cell was found: L: 30, B: 36.8, Is: 9.2 µm (the isthmus is particularly narrow). Lenzenweger (1997: 113, pl. 33: 15) gives: L: 30-33, B: 32-38, Is: 12-13 µm. The population from the Outer Hebrides is slightly larger. There is possible confusion with other 5-radiate taxa but well observed populations are clearly defined.
Cell dimensions: L: 30-36 µm; B: 32-41 µm; Is: 9-16 µm.
Found in oligo-mesotrophic waters including with Sphagnum, but rarely recorded.
References:
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Grönblad, R. (1963). Desmids from Jämtland, Sweden and adjacent Norway.
Lenzenweger, R. (1997). Desmidiaceenflora von Österreich, Teil 2.