Molecular-assisted alpha taxonomy reveals pseudocryptic diversity among species of Bossiella (Corallinales, Rhodophyta) in the eastern Pacific Ocean

A floristic survey of the red algal genus Bossiella was conducted using molecular-assisted alpha taxonomy (MAAT). The MAAT approach used DNA sequence data as a first pass to assess species diversity followed by additional study including detailed morphological observations to delimit species. In addition, type specimen sequencing was conducted to apply existing species names to genetic groups. Four Bossiella species were recognised in the eastern Pacific Ocean based on morphology, but a genetic screen using a DNA barcode marker, mitochondrial cytochrome c oxidase subunit 1 (COI-5P), showed 17 genetic species groups. Due to the large number of species requiring taxonomic assessment, we focused this study on species with predominantly dichotomous branching, that is, the recognised morphospecies B. californica and B. orbigniana. DNA sequences from three loci, psbA, rbcL and COI-5P, resolved five species: B. californica, B. dichotoma, B. schmittii, Bossiella heteroforma sp. nov. and B. orbigniana (the only species with a type locality not in the northeast Pacific). Morphology alone was an inadequate discriminator of these species, but incorporating distribution and habitat data facilitated identification of some species without DNA sequencing. All of these species were widely distributed in the northeast Pacific Ocean, from at least northern British Columbia, Canada, to Monterey Bay, California, USA, with two reaching Baja California Norte, Mexico.