Phylum: Charophyta   Family: Desmidiaceae

Staurastrum longipes  (C.F.O. Nordstedt) E. Teiling 1946

First described and illustrated by Nordstedt (1873: 35, pl. 1: 17) as Staurastrum paradoxum var. longipes. It was later raised to species level by Teiling (1946: 80, fig. 23).
Overall cell dimensions: L: 50-75 µm; B: 60-100 µm; Is: 7.5-9.5 µm.
West, West & Carter (1923: 104) record this species as common in the plankton over much of Britain. It has been infrequently recorded in the Outer Hebrides in recent times.

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