Phylogeny and distribution of the genus Pikea (Gigartinales, Rhodophyta) with special reference to P-yoshizakii from Korea

Four species have been described in the genus Pikea (Dumontiaceae, Gigartinales): three species from North America and one species from Japan. However, the phylogeny and species delimitation in Pikea remain poorly resolved. Here we provide both rbcL and cox1 sequences for all species of Pikea, including the type of P. pinnata and a paratype of P. robusta. Our data reveal that P. californica, P. pinnata and P. yoshizakii are distinct in both data sets, but P. robusta is synonymous with the earlier-described P. pinnata. Morphological and molecular data show that Pikea from Korea is identical to P. yoshizakii and that the previous report of P. californica in Korea is a misidentification. The genus Pikea is well resolved in the main clade of the Dumontiaceae. This is the first study on the phylogeny of Pikea using rbcL and cox1 sequence data.