Phylum: Rhodophyta   Family: Baniaceae

Bangia atropurpurea  (Mertens ex Roth) C.Agardh 1824

Red filamentous alga found in freshwater, brackish and marine inter-tidal habitats. Comprises unbranched, filaments which are uniseriate and the later multiseriate. It has been proposed that the freshwater populations should be classified as a separate species.

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