Genomic and phylogenetic analysis of Ceramium cimbricum (Ceramiales, Rhodophyta) from the Atlantic and Pacific Oceans supports the naming of a new invasive Pacific entity Ceramium sungminbooi sp nov.

The filamentous marine red alga Ceramium cimbricum was described from Denmark, but the name has since been applied to populations worldwide. To determine if C. cimbricum from the Pacific is conspecific with C. cimbricum from the Atlantic, we (1) deciphered an authentic rbcL sequence for the lectotype specimen of C. cimbricum, (2) performed phylogenetic analysis on Pacific and Atlantic C. cimbricum, and (3) assembled and analyzed the complete mitochondrial and plastid genomes of specimens of C. cimbricum from Denmark and California. The lectotype sequence of C. cimbricum was unique and fully resolved with other Atlantic Ceramium species, however, the specimens of C. cimbricum from Denmark, Norway, California, Oregon, and Korea formed a clade with Pacific species. The plastid and mitochondrial genomes of C. cimbricum from Denmark and California were similar in length and gene content, differing by only 67 SNPs and nine gaps for the plastid, and by 100 SNPs and 31 gaps for the mitochondrial genomes. These results support the continued application of the name C. -cimbricum to specimens from Denmark, and warrant the naming of a new species, Ceramium sungminbooi sp. nov., native to Asia and introduced to the northeastern Pacific and Europe.