Epitypification and redescription of Corallina officinalis L., the type of the genus, and C. elongata Ellis et Solander (Corallinales, Rhodophyta)

Corallina L. is the type genus of the subfamily Corallinoideae (Aresch.) Foslie and Corallina officinalis L. is the type species of the genus. This name has been applied worldwide, particularly in temperate waters. An attempt to obtain sequence data from the lectotype specimen was not successful. In order to establish a species concept for C. officinalis based on molecular sequence data as well as morphology, an epitype was selected from Devon, England within the vague type locality 'in O [Oceano] Europaeo', and from which mitochondrial (cox1) and plastid (rbcL) data were obtained. A second species, Corallina elongata Ellis et Solander (type locality Cornwall, England), was shown previously to include at least two species based on DNA sequences. The lectotype of C. elongata is an illustration and therefore an epitype was selected to provide molecular sequence data, using the same markers as for C. officinalis. These molecular sequences for C. officinalis and C. elongata are compared with those of a third, recently described species from Great Britain, Corallina caespitosa R. H. Walker, J. Brodie et L. M. Irvine: these data provide an example for studying Corallina species taxonomy and diversity in other parts of the world. The implications of this work are discussed in relation to concepts of species distribution.