Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus crassus (W. & G.S. West) M.-B. Florin 1957

First described and illustrated by W. & G.S. West (1903: 541, pl. 14: 8-9) as Arthrodesmus crassus. It was later moved by Florin, M.-B. (1957: 130) to its current genus. Florin’s entry reads: Staurodesmus crassus (W. & G. S. West) n. comb. (July 31, 1947). – There is no clarification as to what the 1947 date refers to. Coesel & Meesters (2013: 20) surprisingly made this a variety of Staurodesmus controversus even though they note there is no overlap in size.
Cell dimensions: L: 15-24 µm; B: 16-23 µm.; Is: 7-13 µm; Th: 9.4-12.5; Sp: 1-3.
A rare species, most likely to be found in Atlantic regions in oligotrophic acidic waters.

References: 
Coesel, P.F.M. & Meesters, K.J. (2013) European Flora of the Desmid Genera Staurastrum and Staurodesmus.
Florin, M.-B. (1957). Plankton of fresh and brackish waters in the Sodertalge area.
Teiling, E. (1967). The desmid genus Staurodesmus. A taxonomic study.
West, W. & West, G.S. (1903). Scottish freshwater plankton: I.