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.
Cell dimensions: L: 120-150 µm; B: 65-85 µm; Is: 13-30 µm; Th: 35-58; L/B: 1.70-1.90.
Differs from the nominate variety in having more produced upper lateral and apical lobes. This gives rise to more pronounced incurvations. 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.
Raciborski, M. (1885) Opisy nowych desmidyjów polskich. De nonnullis Desmidiaceis novis vel minus cognitis quae in Polonia inventae sunt.