Taxonomic re-examination of "Chloromonas nivalis (Volvocales, Chlorophyceae) zygotes" from Japan and description of C. muramotoi sp. nov

• Published in: PloS one Vol. 14; no. 1; p. e0210986
• Main Authors: Matsuzaki, Ryo, Nozaki, Hisayoshi, Takeuchi, Nozomu, Hara, Yoshiaki, Kawachi, Masanobu
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 24.01.2019; Public Library of Science (PLoS)
• Subjects: Algae; Biology and Life Sciences; Cell walls; Chloromonas nivalis; Chlorophyceae - classification; Chlorophyceae - genetics; Chlorophyceae - ultrastructure; Cladistic analysis; Computer and Information Sciences; Cysts; Deoxyribonucleic acid; DNA; DNA, Algal - genetics; Ecosystem biology; Ecosystems; Electron microscopy; Environmental studies; Flanges; Germination; Green algae; Japan; Life cycle engineering; Life cycles; Microscopy, Electron, Transmission; Morphology; National parks; New species; Phylogeny; Physical characteristics; Research and Analysis Methods; Scanning electron microscopy; Scanning microscopy; Sequence Analysis, DNA; Snow; Species Specificity; Strain analysis; Taxonomy; Vegetative cells; Zygote - ultrastructure; Zygotes; Japan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0210986

Recent molecular data has strongly suggested that field-collected cysts of snow algae that are morphologically identifiable as the zygotes of Chloromonas nivalis are composed of multiple species. Motile vegetative cells, however, have not been directly obtained from these cysts because of the difficulties involved in inducing their germination. Recently, our comparative molecular analyses, using both field-collected and cultured materials, demonstrated that one Japanese lineage of "C. nivalis zygotes" belongs to C. miwae. Herein, we examined another Japanese lineage of field-collected "C. nivalis zygotes" and a new strain originating from Japan. Our molecular data demonstrated that these two different life cycle stages are conspecific, and that they represent a new species that we herein describe as C. muramotoi sp. nov., based on the vegetative and asexual morphological characteristics of the strain. Multigene phylogenetic analyses showed that this new species was sister to C. miwae. Scanning electron microscopy demonstrated that the cysts of C. muramotoi are different from those of C. miwae, based on the arrangement of the flanges developing on the cell wall.