The 2011 edition of “The Freshwater Algal Flora of the British Isles”: additions, corrections, nomenclatural and taxonomic changes

Taxonomic, nomenclatural and distributional changes since the publication of the 2011 edition (reprinted 2021) of The Freshwater Algal Flora of the British Isles (“Flora”) are reviewed together with some changes overlooked earlier. Many of the more recent changes are a result of studies combining an analysis of morphological and DNA sequence data. Of the 473 changes reported most concern the Chlorophyta (131) and the Charophyta (156) followed by the Cyanobacteria (101), with most of the alterations to the Charophyta involving the desmids (136). Also included are 83 new additions to the British and Irish freshwater algal floras, including 20 overlooked in the Flora. Most of these additions are new records: four are newly described desmids and Synura hibernica (Ochrophyta, Chrysophyceae, Synurales) and Chlorococcum turfosum (Chlorophyta, Chlorophyceae, Chlamydomonadales) are also new. The new additions to Flora include information on locality, collector and publication source. Reference is made to discussions in the Flora giving reasons why some genera and species combinations were not accepted, particularly concerning the Cyanobacteria for which a relatively conservative approach had been adopted in the previous edition of the Flora.