Phylum: Charophyta   Family: Desmidiaceae

Staurastrum spongiosum L.A. de Brébisson ex J. Ralfs 1848

First described by Brébisson in Ralfs (1848: 141, pl. 23: 4a-c) and illustrated by Jenner.
Overall cell dimensions: L: 45-75 µm; B: 40-63 µm; Is: 18-25 µm.
Widespread in acidic habitats such as moorland pools and abandoned peat-cuttings, but not common.

References: 
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. & Carter, N. (1923). A Monograph of the British Desmidiaceae, Volume 5.