Resolving species diversity in the red algal genus Callophyllis (Kallymeniaceae, Gigartinales) in Canada using molecular assisted alpha taxonomy

The COI-5P DNA barcode (the 5′ region of the mitochondrial cytochrome c oxidase I gene) has proven an effective tool for quickly screening large numbers of biological specimens and assigning them to genetic species groups for subsequent examination in an approach known as molecular-assisted alpha taxonomy (MAAT). In the present study, we applied MAAT to Canadian species of the red algal genus Callophyllis in order to resolve confusion surrounding this taxonomically perplexing group. A total of 563 Callophyllis specimens were examined (either molecularly, morphologically or both) – 504 from British Columbia along the Pacific coast of Canada and 59 from the U.S.A., Australia and Chile. In total, 16 genetic species groups were resolved including 12 in Canada although only nine species are reported in the flora. Here we report range extensions of C. beringensis and C. radula from the NW Pacific, C. dissecta from California, U.S.A. and the Chilean species C. variegata (the type species) into the Canadian flora. Our results also uncovered cryptic diversity in the genus necessitating the description of C. schneideri Clarkston & G.W. Saunders sp. nov. Subsequent analyses of a subset of specimens using the internal transcribed spacer of the ribosomal cistron (ITS) resolved the same groups as COI-5P while the universal plastid amplicon (UPA, domain V of theplastid 23S rRNA gene) had poor resolution at the species level and in one case underestimated species diversity. Finally, large-subunit ribosomal DNA (LSU), nuclear elongation factor 2 (EF2), COI-5P and a combined LSU, EF2 and COI-5P alignment were subjected to phylogenetic analyses in order to investigate relationships among Canadian species of Callophyllis. A significant outcome was the resolution of two well-supported lineages for the monocarpogonial versus polycarpogonial species of this genus, as had been posited in the literature.