Phylum: Charophyta   Family: Desmidiaceae

Staurastrum vestitum var. subanatinum W. & G.S. West 1902

A medium-sized cell with an open sinus. Semicells cup- or bowl-shaped with the apex more or less truncate embellished with up to six emarginate granules. The lengthy processes are divergent to varying degrees with about four spines at the tips. In face-view there are two subapical bifurcate spines. In apical view these two bifurcate spines show prominently. This taxon differs from the nominate in its divergent and longer processes and truncate apices.
The authors named it because of its similarity to St. anatinum in face-view. Surprisingly, Coesel & Meesters (2013: 63) made this a variety of St. anatinum, seemingly overlooking the fundamental diagnostic feature being the two bifurcate subapical spines. Consequently, they have added another characteristic to what is already a species complex.
Overall cell dimensions: L: 34-44 µm; B: 70-78 µm; Is: 11.6-12/1 µm, L/B: 0.49-0.60.
Found in slightly acidic habitats such as in the plankton of lochs, especially at altitude. It has also been found in moorland pools with Sphagnum. It’s infrequently recorded in the Outer Hebrides.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
West, W. & West, G.S. (1902). A contribution to the freshwater algae of the north of Ireland.