A Proposal for the Lectotype Designation of Ishige foliacea (Phaeophyceae, Ishigeaceae) Using DNA Barcoding

Abstract

Three species of the genus Ishige (Phaeophyceae, Ishigeaceae) are known from Korea, Japan and Mexico; they include Ishige foliacea Okamura, I. okamurae Yendo and I. sinicola (Setchell and N.L. Gardner) Chihara. Two species, I. foliacea and I. okamurae, are present in the algal flora of Korea and Japan. The original description of I. okamurae defined two forms of branches, filiform and foliose, but later the foliose branch was recognized as a new species I. foliacea, which is epiphytic on I. okamurae but can also be free-living. The currently proposed lectotype for I. foliacea is based on a free-living form and does not reflect the intent of the original description of the species. In this study, we conducted the DNA barcoding for herbarium specimens to identify Ishige species. Additionally, the variation in cox3 sequences obtained from I. okamurae specimens with two morphological forms collected from waters around the Korean Peninsula was sufficient to separate two species, I. okamurae and its epiphyte I. foliacea. The epiphytic I. foliacea on the lectotype specimen of I. okamurae is designated as lectotype I. foliacea.