Phylum: Ochrophyta   Family: Synurophyceae

Synura sphagnicola (Korshikov) Korshikov

As the name suggests, largely found with Sphagnum and not uncommon, but under-recorded

References: 
John, D.M., Whitton, B.A. & Brook, A.J. (2011) The Freshwater Algal Flora of the British Isles