Reinstatement of Corallina chilensis (Corallinaceae, Rhodophyta) based on DNA sequencing of the type material collected by Darwin

To determine whether Corallina chilensis is a distinct species or a variety (i.e. C. officinalis var. chilensis) of the generitype of Corallina, molecular phylogenetic analyses were performed using psbA, COI-5P, rbcL, or some combination of these gene regions from 75 voucher specimens representing Corallina collections from around the world. Names were applied by comparing these DNA sequences with sequences obtained from type specimens, including a 263 bp rbcL sequence from an isotype of C. chilensis collected by Darwin (C. Darwin 2151) from Valparaiso, Chile. DNA sequences from the C. chilensis isotype matched unnamed coralline DNA sequences from British Columbia, Canada, and previously published DNA sequences from the northeast and southeast Pacific. The clade containing the isotype of C. chilensis was distinct from C. officinalis specimens in phylogenetic analyses. Although morphologically variable, fronds of C. chilensis from British Columbia populations matched Kutzing's original description of C. officinalis var. chilensis. These data support the conclusion that C. chilensis is a distinct species, not a variety of C. officinalis, and is distributed in both hemispheres. While this study strongly supported C. chilensis as a distinct species, phylogenetic relationships among Corallina species remain elusive because individual gene trees are not congruent.