Phylum: Charophyta   Family: Closteriaceae

Closterium attenuatum J. Ralfs 1848

First described in Ralfs (1848: 169, pl. 29: 5) and illustrated by Jenner. As the specific epithet suggests, this species is characterised by the fact that the cells narrow rather abruptly towards the apices.
Cell dimensions: L: 400-680 µm; B: 28-45 µm.; Ap: 6-9 µm; L/B: 12-24.
Widely distributed in acidic conditions such as peaty pools and abandoned peat-cuttings, but infrequently recorded.

References: 
Brook, A.J. & Williamson, D.B. (2010). A Monograph on some British Desmids.
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
Ralfs, J. (1848). The British Desmidieae.
Van Westen, M. (2024). Sieralgen in Drenthe.