Re-examination of the morphological characteristics and rbcL gene sequences of Chara zeylanica Willdenow (Charales, Charophyceae) in Korea

• Sites where Chara zeylanica are growing were discovered for the first time since 1977.
• The morphology of 42 Korean specimens was consistent with the description of C. zeylanica..
• The rbcL molecular data of C. zeylanica from Korea were presented for the first time.
• RbcL sequences of C. zeylanica from two populations in Korea were the same.
• RbcL sequences of two populations in Korea were same with the NCBI data of C. zeylanica reported from Japan, China, Israel, USA, Nicaragua, Mexico, and Guatemala.

The genus Chara (Linnaeus, 1753) comprises three sections, Chara, Desvauxia, and Grovesia. The subsection Willdenowia (Wood, 1962) of Grovesia is characterized by having the lowest branchlet segment without cortication. One species, Chara zeylanica sensu lato is attributed to the subsection Willdenowia. However, the taxonomy within this genus remains unclear due in part to the considerable overlap in morphological characteristics. Korean C. zeylanica was first reported in 1997, based on the only two dried specimens to have been collected (in 1960 and 1977). However, we recently discovered new growth sites of C. zeylanica plants in Korea. An investigation of the morphological characteristics of 42 specimens collected from these two sites and the rbcL sequences of two isolates from each site was performed to clarify this taxonomic entity in Korea. A total of 41 rbcL DNA sequences, including 39 previously published sequences, were analyzed using the neighbor-joining method. We identified the plants as C. zeylanica based on a combination of their morphological characteristics—such as the dimensions of the thallus, number of branchlets in a whorl, cortication pattern of branchlets, stipulode arrangement, oogonium traits— and the rbcL gene sequences. The rbcL sequences of Korean isolates were identical to those of C. zeylanica from Central America, the USA, China, Japan, and Israel. The sequences of Korean isolates differed from those of species from New Caledonia, Taiwan, Sri Lanka, and Australia by one to two bases. All populations of C. zeylanica, with the exception of those from Australia and Taiwan, formed a single clade. This is the first report of the sequence of the plastid rbcL gene of C. zeylanica in Korea.