Phylum: Charophyta   Family: Desmidiaceae

Staurastrum meriani P.F. Reinsch 1866

First described and illustrated by Reinsch (1867: 125; pl. 23: D1, 1-11). West & West (1912: 123) regarded this as “… a very distinctive upland species.” For Scotland it’s described as “General, but scarce.”
Overall cell dimensions: L: 35-50 µm; B: 20-28 µm; Is: 13-18 µm.
An Arctic-alpine species confined to the north-west in Britain. The habitat is shallow, vegetated, pools and cuttings but also with bryophytes on dripping rocks, where it’s frequently found.

References: 
Coesel, P.F.M. & Meesters, K.J (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Reinsch, P.F. (1867). De speciebus generibusque nonnullis novis ex Algarum et Fungorum classe.
West, W. & West, G.S. (1912). A Monograph of the British Desmidiaceae, Volume 4.