A phylogenetic investigation of the genus Spyridia (Callithamniaceae, Rhodophyta) in Bermuda uncovers four new species.

In a molecular-assisted alpha taxonomic study of the genus Spyridia in Bermuda, several new species were discovered in a complex previously recognized as the two species S. aculeata and S. filamentosa in the islands. Known in Bermuda since 1857, S. aculeata is genetically confirmed for all isolates bearing uncinate spines on their determinate branches, thus including all specimens that had in the past been identified as S. complanata and S. hypnoides. The most abundant species in the flora is S. consimilis sp. nov. found subtidally around the islands and historically thought to be S. filamentosa, a species with which it is morphologically cryptic. The other three new genetically distinct species are also non-uncinate: S. bernatowiczii, S. rhizoidea, and S. struanii. Spyridia bernatowiczii would have likely been also identified as S. filamentosa in the past and is genetically and morphologically distinct from S. consimilis. The remaining two species are smaller, forming cushions or tufts in intertidal and shallow subtidal habitats.