Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus ralfsii (West) Tomaszewicz 1988

West (1892: p. 168) described this as a new species as Arthrodesmus ralfsii, split from Arthrodesmus incus Ralfs (1848: p. 118, pl. 20: 4). Later, Tomaszewicz (1988: p. 62) moved it to the replaced genus Staurodesmus. Found in acidic moorland pools and bogs. Current status in the Outer Hebrides is uncertain.

References: 
Ralfs, J. (1848) The British Desmidieae.
West, W. (1892) A contribution to the freshwater algae of west Ireland.
Tomaszewicz, G.H. (1988) Desmids of the transitional bogs of the Middle Mazowsze Lowland.
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus.