Phylum: Charophyta   Family: Desmidiaceae

Xanthidium fasciculatum var. oronense W. & G.S. West 1896

First described and illustrated by West & West (1896: 253, pl. 15: 25). They describe this as 'An American variety', and note that the nominate is rare in Britain. The varietal epithet is named after Orono, a town in Maine, USA. It differs in having a quite large granule within each basal angle.
Overall cell dimensions: L: 60-70 µm; B: 60-70 µm; Is: 14-16 µm.
Over 100 years after the Wests’ record, both this and the nominate variety are rare in Britain. The Outer Hebridean finds have mainly come from acidic shallow lochs and lochans.

References: 
John, D.M. & Williamson, D.B. (2009). A Practical Guide to the Desmids of the West of Ireland.
West, W. & West, G.S. (1896). On some North America Desmidieae.