RETRACTED ARTICLE: Derbesia maxima sp. nov. (Bryopsidales, Chlorophyta) from Korea based on morphological and molecular data

A green alga was collected from Daejin, located on the eastern coast of Korea. It shows a typical siphonous thallus structure composed of erect and prostrate filaments like other Derbesia sporophytes and is characterized by a relatively large sporophytic thallus (6–8 cm) without calcified attachment disk, irregularly or subdichotomously branched filaments with a basal septum and 1(2) pyrenoid per ovoid to lenticular, occasionally irregular chloroplast. Sporangia have an obovoid or pyriform shape with a short pedicel and septum at the base. Vesicular gametophytes are spherical or ovoid, with short anchoring stalk and rhizoids. A heteromorphic life history alternating between sporophytic filaments and gametophytic Halicystis stage was observed. In a phylogenetic tree based on rbc L sequence, the Korean entity nests in a sister clade to several species groups including the type Derbesia marina , and of these species, D. fastigiata is closest to the Korean alga with a genetic divergence of 3.1%. However, it is distinguished from the Korean species by the size of sporophytic thalli, branching pattern, basal constriction of laterals, and shape of sporangia. The other species forming the sister clade are also distinguished from the Korean entity by general morphological features of sporophytes and gametophytes. The specific distinction of the Korean alga from those species is supported by its genetic divergence, which is considered to be involved in the inter-specific range for the genus based on the previous data. Accordingly, Derbesia maxima sp. nov. is proposed for this siphonous green alga from Korea.