Phylum: Charophyta   Family: Closteriaceae

Closterium angustatum J. Ralfs 1848

First described by Ralfs (1848: 172, pl. 29: 4) and illustrated by Jenner. The specific epithet means 'narrowed' referring to the pinched area below the apices. This gives a swollen appearance to the apices.
Cell dimensions: L: 280-400 µm; B: 17-28 µm; Ap: 10-15 µm; L/B: 12-20.
A widespread and locally common species found in acidic habitats such as peat bogs. It is frequently found with Sphagnum.

References: 
Brook, A.J. & Williamson, D.B. (2010). A Monograph on some British Desmids.
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Ralfs, J. (1848). The British Desmidieae.
West, W. & West, G.S. (1904). A Monograph of the British Desmidiaceae, Volume 1.