Rhodogorgon truncata sp. nov. (Rhodogorgonales, Rhodophyta), a new red alga from the west coast of Thailand

The recognition of new species is fundamental to understanding biodiversity and biogeography. Through an integrative taxonomic approach, combining morphological and multilocus molecular data, a new red algal species, Rhodogorgon truncata sp. nov. is described from the west coast of Thailand. The new species differs from the two previously described species in the genus, i.e. R. ramosissima and R. flagellifera, by unique morphological features including compressed and stocky thalli with determinate short branchlets along the upper portion, giving it a truncated and verrucose appearance. Our morphological observations revealed the smaller size, compressed shape, and truncated apices of R. truncata in contrast to the cylindrical, irregularly branched thalli of R. ramosissima and R. flagellifera. Phylogenetic analyses suggest that R. truncata is more closely related to undescribed Rhodogorgon specimens from the Indo-Pacific than to the Caribbean R. ramosissima. The discovery of this new species expands the known diversity within the genus Rhodogorgon and suggests greater, as yet undiscovered, species diversity among poorly studied red algae in the Indo-Pacific Ocean.