Phylum: Charophyta   Family: Desmidiaceae

Euastrum oblongum J. Ralfs 1848

Just above the isthmus of the semicell is a large protuberance with two smaller ones either side. Two more appear in the upper part of the semicell. There is a central scrobiculus in most cells, but occasionally lacking.
Cell dimensions: L: 140-200 µm; B: 70-100 µm; Is: 20-33 µm; Th: 46-65 µm; L/B: 1.70-2.20.
Widespread and common in acidic moorland pools and bogs, but also tolerant of less acidic conditions. Usually found in mesotrophic waters at the benthic level or in the tychoplankton.

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