Abstract
The new species Asterochloris sejongensis sp. nov. has been collected from four localities of King George Island, Antarctica, and is described as a phycobiont of the lichen species Cladonia pyxidata and Sphaerophorus globosus. This discovery is based on morphological and molecular data obtained using light microscopy, confocal laser microscopy, transmission electron microscopy, and two molecular markers; nuclear internal transcribed spacer (ITS) rDNA and actin genes. This species is characterized by five unique hemi-CBCs in the nuclear ITS transcripts, deeply lobed and echinulate chloroplasts (depending on the life stage), and two rows of pyrenoglobuli associated with two thylakoid envelopes. A molecular phylogenetic analysis of the ITS and actin gene sequences indicated that this new species is closely related to A. woessiae and forms a distinct well-supported lineage with the genus.