Phylum: Cyanobacteria   Family: Microcystaceae

Aphanocapsa grevillei (M.J. Berkeley) L. Rabenhorst 1865

First described and illustrated by Berkeley (1832: 16, pl. 5: 1) as Palmella grevillea. It was later moved by Rabenhorst (1865: 50) to its current position.
Cell diameters: 3.2-5.6 µm.
Found in peaty habitats such as moorland pools and disused peat-cuttings. Distribution and status in the Outer Hebrides is unknown but probably fairly common.

References: 
Berkeley, M.J. (1832). Gleanings of British algae; being an appendix to the supplement to English Botany.
John, D.M., Whitton, B.A. & Brook, A.J. (2011 second edition). The Freshwater Algal Flora of the British Isles.
Rabenhorst, L. (1865). Flora europaea algarum aquae dulcis et submarinae. Sectio II. Algas phycochromaceas complectens.