Phylum: Charophyta   Family: Mesotaeniaceae

Mesotaenium chlamydosporum var. minus W. West & G.S. West 1904

First legally described by West & West (1904: 53) as Mesotaenium chlamydosporum forma minor. AlgaeBase and other authors now refer to it as M. chlamydosporum var. minus so I have followed their lead. However, I can’t find any reference to it having been raised to a variety. Mature cells are elliptical but in any given population there will be numerous immature cells, which are tapered and smaller. Cell content can be coloured purple to violet but this pigment is often lacking. Very similar to the nominate variety but smaller. Chloroplast in face-view only filling part of the cell. However, the purple sap content can fill the cell.
Cell dimensions: L: 13-20 µm; B: 10-12 µm; L/B: 1.3-1.8.
Found in mucilaginous masses atmophytically on moss and other substrates.

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