title: Taxonomic revision of Chlamydomonas subg. Amphichloris (Volvocales, Chlorophyceae), with resurrection of the genus Dangeardinia and descriptions of Ixipapillifera gen. nov. and Rhysamphichloris gen. nov.
abstract: Chlamydomonas (Cd.) is one of the largest but most polyphyletic genera of freshwater unicellular green algae. It consists of 400-600 morphological species and requires taxonomic revision. Toward reclassification, each morphologically defined classical subgenus (or subgroup) should be examined using culture strains. Chlamydomonas subg. Amphichloris is characterized by a central nucleus between two axial pyrenoids, however, the phylogenetic structure of this subgenus has yet to be examined using molecular data. Here, we examined 12 strains including six newly isolated strains, morphologically identified as Chlamydomonas subg. Amphichloris, using 18S rRNA gene phylogeny, light microscopy, and mitochondria fluorescent microscopy. Molecular phylogenetic analyses revealed three independent lineages of the subgenus, separated from the type species of Chlamydomonas, Cd. reinhardtii. These three lineages were further distinguished from each other by light and fluorescent microscopy-in particular by the morphology of the papillae, chloroplast surface, stigmata, and mitochondria-and are here assigned to three genera: Dangeardinia emend., Ixipapillifera gen. nov., and Rhysamphichloris gen. nov. Based on the molecular and morphological data, two to three species were recognized in each genus, including one new species, I. pauromitos. In addition, Cd. deasonii, which was previously assigned to subgroup "Pleiochloris," was included in the genus Ixipapillifera as I. deasonii comb. nov.
authors.affiliation: Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, 252-0882, Japan.|Institute for Advanced Biosciences, Keio University, Kakuganji, Tsuruoka, 997-0052, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakada
authors.affiliation: Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa, 252-0882, Japan.|Institute for Advanced Biosciences, Keio University, Kakuganji, Tsuruoka, 997-0052, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Tomita
authors.affiliation: Biodiversity Research Center, Academia Sinica, Nankang, Taipei, 11529, Taiwan.
authors.forename: Jiunn-Tzong
authors.initials: JT
authors.lastname: Wu
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bukyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Nozaki
mesh_terms: D001483:Base Sequence; D001499:Bayes Theorem; D002696:Chlamydomonas / Q000145:classification* / Q000166:cytology / Q000235:genetics; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics
chemical_list: D012337:RNA, Ribosomal, 18S
keywords: Chlamydomonas subg. Amphichloris; Dangeardinia; Ixipapillifera; Rhysamphichloris; Volvocales; mitochondria; molecular phylogeny; morphology; new species; taxonomy