Phylum: Chlorophyta   Family: Sphaeropleaceae

Radiofilum flavescens  G.S. West

Rare in the British Isles and new to the Outer Hebrides in 2022. It prefers boggy circumneutral pools and ditches

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