Taxonomic changes in the Lomentariaceae (Rhodymeniales, Rhodophyta): Yendoa gen. nov. and Ceratodictyon sanctae-crucis sp. nov.

ABSTRACT The Lomentariaceae, previously treated as subfamily Lomentarioideae in the family Champiaceae, is one of the six families currently classified in the Rhodymeniales. Relationships within the family are not well-established, and new genera have been segregated from Lomentaria, a notoriously polyphyletic taxon as currently circumscribed. The lack of access to molecular data of type specimens has limited the taxonomic clarifications within the Lomentariaceae. Using new collections from Brazil, historical collections and data available in GenBank, we generated rbcL and COI-5P phylogenies of the Lomentariaceae, and we used species delimitation methods to assess the species-level diversity among sequences. A nuclear LSU rDNA phylogeny, although less representative in number of taxa, confirmed our findings. Our results recovered Ceratodictyon and Semnocarpa as monophyletic, whereas Lomentaria was polyphyletic. Integrating phylogenetic analyses, analyses of genetic variance, and morphological analyses, we revealed a new species, Ceratodictyon sanctae-crucis sp. nov., collected on the coast of Bahia (northeastern Brazil). Having included a newly generated sequence of the holotype of Lomentaria sinensis, a heterotypic synonym of L. hakodatensis, and a sequence from a sample collected near the type locality of L. hakodatensis, we propose the new genus Yendoa gen. nov. to accommodate this species. Our results support a more phylogenetically coherent taxonomic scheme for the Lomentariaceae, which now includes only monophyletic genera.