Phylum: Charophyta   Family: Closteriaceae

Closterium juncidum var. brevius J. Roy 1910

Differs from the nominate variety in being broader both at the centre and apices. The relatively acidic habitat remains the same as the nominate.
Cell dimensions: L: 200-425 µm; B: 13-18 µm; Ap: 7.7-10.6 µm; L/B: 18+.
Status in the Outer Hebrides uncertain as it may have been misidentified in the past.

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.