Phylum: Charophyta   Family: Desmidiacea

Xanthidium hebridarum (W. & G.S. West) P.F.M. Coesel & K.J. Meesters 2023

First described and illustrated by West & West (1905: 500, pl. 7: 21) as a variety of Xanthidium antilopaeum. Recently, Coesel & Meesters (2023: 195) raised it to species level. This species is distinguished by the presence of three single spines each side of the semicells, although occasionally one can be twinned (usually the apical one).
Cell dimensions: L: 46-54 µm; B: 42-49 µm; Is: 16-18 µm; Sp: 6-13 µm; Overall LxB: 52-71 x 65-82 µm.
A scarce desmid found in variously acidic waters such as loch-margins and moorland pools.

References: 
Coesel, P.F.M. & Meesters, K.J. (2023 second edition). Desmids of the Lowlands.
West, W. & West, G.S. (1905). Further contribution to freshwater plankton of the Scottish lochs.