A reappraisal of Symphyocladia (Rhodomelaceae, Rhodophyta), including a new species based on morphology and molecular data

Abstract

Kim S.Y., Nelson W. and Kim M.S. 2012. A reappraisal of Symphyocladia (Rhodomelaceae, Rhodophyta), including a new species based on morphology and molecular data. Phycologia 51: 531–541. DOI: 10.2216/11-62.1Comparative morphological investigations and molecular analyses of rbcL data are used to critically reassess the genus Symphyocladia and to examine phylogenetic relationships with the type species, S. marchantioides. Specimens collected from the type locality in New Zealand confirm that S. marchantioides can be identified by the presence of numerous apical cells on the growing margin producing axial systems that remain congenitally laterally attached, branched trichoblasts arising marginally and close to dormant apical cells, six to eight pericentral cells, and lacking cortication. Symphyocladia jejuinsula sp. nov is newly described for samples from the southern coast of Korea, and is characterized by thin and flat thalli to 10 cm in height, 8–10 pericentral cells, lack of trichoblasts, 10 segments of congenital fusions, cortication in the lower part of branches, and determinate branches each with a sharply pointed apical cell. Molecular analysis of the rbcL gene reveals sufficient sequence divergence to warrant species recognition of six distinct species within Symphyocladia, and the presence of two clusters of species that form sister clades in the phylogenetic tree. The monophyly of Symphyocladia is strongly supported and the genus is clearly separated from Pterosiphonia. These two genera belong in the tribe Pterosiphonieae, having an alternate-distichous branching pattern as their diagnostic character.