Unraveling the Bryocladia scopulorum complex from the Southwestern Atlantic Ocean with the description of three new species of Bryocladia (Rhodomelaceae, Rhodophyta)

The filamentous red algal genus Bryocladia was recently deeply revised based on molecular and morphological data. However, data from the Southwestern Atlantic Ocean are scarce. Here, we provide a phylogenetic study of Bryocladia representatives from the Brazilian coast with new additions to the genus. Our samples were collected from the north to southeastern Brazilian coast in marine and estuarine areas. We carried out a morphological and molecular study based on COI-5P and rbcL gene sequences. Our phylogenetic analyses confirmed the presence of seven species on the Brazilian coast, four of which were previously known: B. cuspidata, B. subtilissima, B. thyrsigera, and B. villum. Three new species are described here, B. itaipensis sp. nov., B. oceanica sp. nov., and B. mucuripensis sp. nov., all morphologically included in the B. scopulorum complex. Bryocladia subtilissima was observed only in Brazilian estuarine areas. However, it was split into two subclades, which require further investigation. The three new species expand the known diversity of the B. scopulorum complex from 12 to 15 species. Bryocladia itaipensis is closely related to B. canariensis and B. caespitosa, whereas B. oceanica and B. mucuripensis formed distinct lineages with unsolved relationships. All new species are restricted to their type localities in Brazilian waters, reinforcing the need for further study of tiny species, especially from the tribes Polysiphonieae and Streblocladieae.