Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus dejectus var. apiculatus (L.A. de Brébisson) H.T. Croasdale 1957

It differs from the nominate variety in having the spines pointing almost vertically and occasionally recurved.
Single cell dimensions: L: 23.1 µm; B: 24.4 µm; Is: 7.2 µm; Sp: 5-6 µm; Overall L: 27.
West, West & Carter (1923), as Staurastrum apiculatum, describe it as “general, but scarce“ for Scotland. There is little to suggest this status has changed since the Wests’ time. Found in circumneutral waters such as loch-margins and pools.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Teiling, E. (1967). The Desmid Genus Staurodesmus. A taxonomic study.
West, W., West, G.S. & Carter, N. (1923). A Monograph of the British Desmidiaceae, Volume 5.