Phylum: Charophyta Family: Desmidiaceae
Cosmarium tetraophthalmum Brébisson ex Ralfs 1848, sensu auct. Nonnull
Similar in size and habitat-requirements to Cosmarium tetraophthalmum but having smaller and more numerous granules. In face-view up to 16 granules can been seen on each side of the semicell. Parts of the cell-wall can be totally lacking in granules and is finely punctate. Because of the confusion with C. tetraophthalmum, its status in the Outer Hebrides in unclear. See Kouwets (in manuscript) for a detailed analysis. He proposed to name this taxon Cosmarium tetraophthalmoides.
Kouwets, F.A.C. (in manuscript) European Flora of the Desmid Genus Cosmarium.