Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus cuspidatus (J. Ralfs) E. Teiling 1967

An extremely variable species both in terms of the extension of the isthmus and the length of the spines, which are usually divergent but can be parallel or even convergent.
Cell dimensions: L: 24-39 µm; B: 20-44 µm.; Is: 5-10 µm; Sp: 4-13; Overall B: up to 61 µm.
Common in fairly acidic to mildly alkaline waters such as the plankton of lochs and moorland bogs and pools.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Van Westen, M.C. (2024). Sieralgen in Drenthe.