Phylum: Charophyta   Family: Closteriaceae

Closterium dianae J. Ralfs 1848

First described in Ralfs (1848: 168: 28, pl. 5a-e) and illustrated by Jenner. This taxon has spawned a number of varieties which are not always easy to separate. Brook & Williamson (2010: 283) in particular give a large range of (bracketed) dimensions.
Cell dimensions: L: 195-325 µm; B: 15-28.5 µm; Ap: 3.2-4.3 µm; Arc: 122-132°; L/B: 11-13.
Zygospore dimension: 48 x 43 µm.
A common species of acidic pools and bogs, also from abandoned peat-cuttings.

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.
West, W. & West, G.S. (1904). A Monograph of the British Desmidiaceae, Volume 1.