Phylum: Charophyta   Family: Closteriaceae

Closterium pronum  L.A. De Brébisson 1856

First described and illustrated by Brébisson (1856: 157, Pl. 2: 42).
Cell dimensions: L: 290-391 µm; B: 7-9 µm; Ap: 2-3 µm; L/B: 32-53.
Infrequently recorded from mildly acidic to slightly alkaline habitats such as moorland bogs and pools.

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.
De Brébisson, L.A. (1856). Liste des Desmidiées, observées en Basse-Normandie.
West, W. & West, G.S. (1904). A Monograph of the British Desmidiaceae, Volume 1.