Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus aristiferus  (J. Ralfs) K. Tomasson 1960

First described by Ralfs (1848: 123, pl. 21: 2) as Staurastrum aristiferum and illustrated by Jenner. Much later it was moved to the genus Staurodesmus by Tomasson (1960: 34).
Cell dimensions: L: 22-31 µm; B: 25-35 µm.; Is: 5.7-8.8 µm; Sp: 6-18; Overall: L: 30-52 x B: 36-63.
A rare species found in the plankton of acidic waters. It has an Atlantic distribution.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013). European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Ralfs, J. (1848). The British Desmidieae.
Thomasson, K. (1960). Notes on the plankton of Lake Bangweulu Part 2.
West, W., West, G.S. & Carter, N. (1923). A Monograph of the British Desmidiaceae, Volume 5.