Phylum: Chlorophyta   Family: Chaetophoraceae

Chaetophora pisiformis (A.W. Roth) B. Liu, Q. Xiong, X. Liu, Z. Hu & G. Liu 2019

First described by Roth (1802: 272) as Rivularia pisiformis. More recently it has been reclassified by B. Wen Liu, Qian Xiong, X. Dong Liu, Z. Yu Hu & G. Xiang Liu (2019: 77).
Little status information for the Outer Hebrides but probably fairly common. It grown on various substrates such as stems of aquatics, rock, molluscs, etc. Found in streams and lochs.

References: 
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition). The Freshwater Algal Flora of the British Isles.
Liu, B., Xiong, Q., Liu, X., Liu, G. & Hu, Z. (2018). Molecular phylogeny and taxonomy of the genus Chaetophora (Chlorophyceae, Chlorophyta), including descriptions of Chaetophoropsis aershanensis gen. et sp. nov.
Roth, A.W.(1802). Neue Beyträge zur Botanik Erster Theil.