Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus extensus var. rectus (B. Eichler & Raciborski) Coesel & Meesters

A recently named variety occupying similar habitats to the nominate variety. Distribution little known in Britain

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus