Phylum: Charophyta   Family: Desmidiaceae

Staurodesmus incus var. indentatus (W. & G.S. West) P.F.M. Coesel 2007

First described and illustrated by West & West (1912: 94, pl. 113: 20-24) as Arthrodesmus incus var. indentatus. It was much later moved to its current genus by Coesel (2007: 12, fig. 27).
Cell dimensions: L: 32-37 µm; B: 24-27 µm; Is: 8-10 µm; Sp: 22-26 µm; Overall LxB: 54-57 x 65-72.
A rare taxon with an Atlantic distribution. Found in slightly acidic lochs with open water.

References: 
Coesel, P.F.M. (2007). Taxonomic notes on Dutch desmids IV: new species, new names, new combinations.
West, W. & West, G.S. (1912). A Monograph of the British Desmidiaceae, Volume 4.