A Catalogue of Irish Seaweeds. 2012. 1 col. pl. 249 p. gr8vo. Hardcover. (ISBN 978-3-905997-10-1)

An updated systematic catalogue of the seaweeds of the island of Ireland is presented with sources, habitats, distributions, and notes on nomenclature, taxonomy and distribution. Included are 570 species: 303 species of Rhodophyta, 93 species of Chlorophyta, 13 species of Vaucheria, and 161 species of Phaeophyceae. Three phyla (Rhodophyta, Chlorophyta, and Ochrophyta), 11 classes (5 Rhodophyta; 4 Chlorophyta; 2 Ochrophyta), 35 orders (19 Rhodophyta; 5 Chlorophyta; 11 Ochrophyta), 91 families (50 Rhodophyta; 16 Chlorophyta; 25 Ochrophyta) are represented. English and Irish vernacular names, and sources for these are given, together with a glossary of Irish names. A list of seaweeds found in Britain but not reported from Ireland to date is given together with distributional, taxonomic, nomenclatural, and other details. A preliminary comparative conservation assessment of 334 speciesof rare or potentially rare species in Britain and Ireland is given (Gigartinales, Rhodophyta), and Schmitziellaceae, M.D.Guiry, D.J.Garbary & G.W.Saunders fam. nov. (Gigartinales, Rhodophyta). Ninety-six species are known from Britain (including two varieties of species not otherwise known to occur in Britain), but not from Ireland: 53 reds, 14 greens, a single Vaucheria, and 28 browns. Twenty of these (18 reds and two browns) are considered to be adventive or potentially adventive, leaving only 76 native species that are found in Britain but not in Ireland, which results in an Irish seaweed flora that is currently about 88% of the native British seaweed flora, contrasting very favourably with a native flowering-plant flora in Ireland of about 50% of that of Britain (approximately 850 vs 1700 species). Worldwide, there are about 9500 species of seaweeds (6200 reds; 1500 greens; 1800 browns). Thus, about 7.5% of the worlds known seaweeds occur in Ireland, which is considerable given its geographical location and range, and its relatively narrow temperature ranges and subtidal light penetration. By contrast, the native Irish flowering plant flora is, at most, 0.25% of the worlds 350-400,000 flowering plant species.