Phylum: Charophyta   Family: Closteriaceae

Closterium abruptum var. brevius (W. & G.S. West) W. & G.S. West 1904

Differs from the nominate variety in having more thick-set and shorter cells.
Cell dimensions: L: 80-151 µm; B: 15-19 µm; Ap: c.4; L/B: 4-8.
It occurs in oligotrophic, weakly acidic waters, often with mosses. It would appear to be much scarcer than the nominate variety.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Van Westen, M.C. (2024). Sieralgen in Drenthe.
West, W. & West, G.S. (1904). A Monograph of the British Desmidiaceae, Volume 1.