Phylum: Charophyta   Family: Closteriaceae

Closterium baillyanum var. parvulum  R. Grönblad 1919

Van Westen (2024: 185) has analysed all his Drenthe data and suggests that too much emphasis has been placed on the L/B ratio whereas the breath is a far better diagnostic criterion. He considers var. parvulum Grönblad to be easily distinguished from var. alpinum based on the cell breadth. I have followed this lead here.
His cell dimensions: L: 260-515 µm; B: 24-34 µm; L/B: 8-16.
My cell dimensions: L: 300 µm; B: 25 µm.; L/B: 12.
Widespread and common where acidic conditions exit, such as peaty pools and abandoned peat-cuttings.

References: 
Brook, A.J. & Williamson, D.B. (2010). A Monograph on some British Desmids.
Van Westen, M.C. (2024). Sieralgen in Drenthe.