A synoptic key to the Rhodophyta of the Western Mediterranean Part. I Gigartinales, Halymeniales, Hildenbrandiales and Plocamiales

A synoptic key for identifying the Gigartinales, Halymeniales, Hildenbrandi ales and Plocamiales from the Western Mediterranean has been prepared in or der to facilitate the recognition of these red algae. The orders Gigartinal es, with some 69 species grouped in 19 families and 35 genera, Halymeniales , with 13 species grouped in 2 families and 6 genera, Hildenbrandiales, wit h 1 family and 1 genera of 3 species, and Plocamiales, with 1 family and 1 genus of 2 species are included. The genus Wurdermannia Harvey is also incl uded in the key, although it has not finally been established whether it be longs to the order Gigartinales or not. Morphological and anatomical descri ptions of the reproductive structures, using data from the literature and f rom personal observations are presented.