Phylum: Charophyta   Family: Mesotaeniaceae

Cylindrocystis gracilis I. Hirn 1953

First described and illustrated by Hirn (1953: 466, figs. 2-3). Cells narrow, cylindrical, occasionally slightly curved, with rounded to truncate-rounded ends. Two chloroplasts each with one or more pyrenoids.
Cell dimensions: L: 24- 48 µm; B: 7.5-11 µm; L/B: 2.5-4.8.
A rare desmid that may have been overlooked or misidentified previously.

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.
Hirn, I. (1953) Vitalfärbungestudien an Desmideen.