Segregating characters used within Amphiroa (Corallinales, Rhodophyta) and taxonomic reevaluation of the genus in the Azores

Abstract

A compilation of the published morphological and anatomical characters used in species diagnosis within the genus Amphiroa (Corallinales, Rhodophyta) was made and their expression was evaluated in 142 specimens collected in the Azores. An evaluation of the genus diversity in this archipelago was undertaken. Morphological and anatomical features here selected as diagnostic characters of Amphiroa in the Azorean plants include shape of the thallus, branching origin, morphology of the apical intergenicula in transverse section, number of cell tiers per mature geniculum and pattern of long vs. short intergenicular tiers of cells. The occurrence of Amphiroa beauvoisii and Amphiroa cryptarthrodia was confirmed in the Azores. The form cyathifera of the species Amphiroa fragilissima is newly reported for the Archipelago. Amphiroa exilis and Amphiroa rigida, the other species recorded in the area, were not observed. A morphological and anatomical account is provided for the studied species and comparisons made with both type material and material from the same species from other regions.