Phylum: Charophyta Family: Desmidiaceae
Staurastrum bulbosum var. cyanthiforme (West & G.S. West) Coesel & Meesters
The Wests (1923), as Staurastrum gracile var. cyathiforme, record it from Lewis in the plankton of lochs. This variety differs from the nominate in having pronounce apical teeth. Status in the Outer Hebrides uncertain
References:
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus
West, W., West, G.S. & Carter, N. (1923) A Monograph of the British Desmidiaceae, Volume 5