Morpho-anatomical and molecular reassessments of Rhodymenia prostrata (Rhodymeniaceae, Rhodophyta) from Japan support the recognition of Halopeltis tanakae nom. nov.

Abstract

ABSTRACT We collected the deep-water species Rhodymenia prostrata (Rhodymeniaceae, Rhodophyta), for the first time in nearly 50 years, from the type locality off Mageshima Island, Japan. Our combined rbcL, cox1 and 28S rDNA analyses suggested that R. prostrata belongs in the genus Halopeltis but is distinct from all other Halopeltis species. However, the binomial Halopeltis prostrata already exists and hence a new epithet was required. Consequently, we propose the new name Halopeltis tanakae for R. prostrata based on morpho-anatomical and molecular analyses. The occurrence of small intercalating cells in H. tanakae is congruent with the generic concept of Halopeltis. Halopeltis tanakae is characterized by a procumbent thallus, crispate blades, cystocarps lacking basal constrictions, cystocarps primarily on blade margins, and mucilaginous strands in cystocarp cavities. Halopeltis tanakae is the second representative of the genus to be reported from the northwestern Pacific.