Phylum: Charophyta   Family: Desmidiaceae

Staurastrum longipes  (Nordstedt) Teiling 1946

Found in the plankton of acidic, oligotrophic water-bodies. The distribution is very much Atlantic, where it is common.

References: 
Nordstedt, O. (1873) Bidrag till kännedomen om sydligare Norges Desmidiéer.
Teiling, E. (1946) Zur Phytoplanktonflora Schwedens.
West, W., West, G.S. & Carter, N. (1923) A Monograph of the British Desmidiaceae, Volume 5.
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus.