Phylum: Charophyta   Family: Desmidiaceae

Euastrum lacustre (E. Messikommer) P.F.M. Coesel 1984

Similar to E. insulare but that species tends to be a little smaller and perhaps occupies a slightly less alkaline habitat.
Cell dimensions: L: 26-33 µm; B: 18-23 µm; Is: 5.5-7.5 µm; L/B: 1.33-1.5.
Infrequently recorded in circumneutral to slightly alkaline waters, such as in the plankton of lochs and marginal vegetation of moorland pools.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Van Westen, M.C. (2024). Sieralgen in Drenthe.