Halymenia johorensis sp. nov. (Halymeniaceae, Rhodophyta), a new foliose red algal species from Malaysia

A new Halymenia species, Halymenia johorensis sp. nov., from southern Peninsular Malaysia is proposed based on plastid-encoded large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) gene analyses and detailed morphological observations. The new species is characterized by having (1) elliptical, oblong, or irregularly shaped blades, incised with some perforations, arising from a narrow-cuneate stipe attached to a discoid holdfast; (2) blades with a cartilaginous and gelatinous texture, a smooth to rugose surface, and irregularly dentate and cleft margins; and (3) isodiametric outer cortical cells and rounded to stellate inner cortical cells. RbcL sequence analyses have shown H. johorensis to be genetically distinct from other Halymenia species. Although H. johorensis is sister to Halymenia plana, these two species can be distinguished both molecularly and morphologically. Further studies are necessary to investigate the phylogenetic relationships and species diversity in this genus.