Phylum: Charophyta   Family: Desmidiaceae

Staurastrum brachiatum J. Ralfs 1848

First described by Ralfs (1848: 131, pl. 23: 9) and illustrated by Jenner. A cell that shows considerable variation, especially in the size and shape of the bi-lobed ends to the processes.
Cell dimensions: L: 27-40 µm; B: 30-45 µm; Is: 7-8 µm.
Usually found in the plankton of shallow, vegetated lochs. Widespread in the Outer Hebrides but not that common.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Ralfs, J. (1848) The British Desmidieae.
West, W., West, G.S. & Carter, N. (1923) A Monograph of the British Desmidiaceae, Volume 5.