Phylum: Charophyta   Family: Desmidiaceae

Euastrum humerosum var. affine (J. Ralfs) M. Raciborski 1885

Semicells pyramidal with double basal lobes and a lateral lobe above the median line. Apices truncate with a deep, closed, median incision. In face view there are 5 protuberances, three across the base of the semicell, and two across the centre. At the base of these two is a noticeable scrobiculum. Differs from the nominate variety in having more produced upper lateral and apical lobes. This gives rise to more pronounced incurvations.
Cell dimensions: L: 112-150 µm; B: 59-85 µm; Is: 16-22 µm; Th: 35-58; L/B: 1.70-1.90.
Rare in acidic habitats such as moorland pools and bogs.

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