Phylum: Charophyta Family: Desmidiaceae
Cosmarium subquadrans var. minus Symoens ex Coesel
More frequent than the nominate variety but still not often encountered. It's interesting that the nominate variety has two pyrenoids per semi-cell whereas this variety has one. Coesel & Meesters (2007) record it as 'var. minor'
Coesel & Meesters (2007) Mesotaeniaceae and Desmidiaceae of the European Lowlands
John, Whitton & Brook (2011) The Freshwater Algal Flora of the British Isles