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

PLoS One. 2019 Jan 24;14(1):e0210986. doi: 10.1371/journal.pone.0210986. eCollection 2019.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chlorophyceae / classification*
  • Chlorophyceae / genetics
  • Chlorophyceae / ultrastructure
  • DNA, Algal / genetics
  • Japan
  • Microscopy, Electron, Transmission
  • Phylogeny
  • Sequence Analysis, DNA
  • Snow
  • Species Specificity
  • Zygote / ultrastructure


  • DNA, Algal

Grant support

RM was supported by Grant-in-Aid for JSPS Research Fellow (No. 16J09828) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT)/Japan Society for the Promotion of Science (JSPS) KAKENHI ( The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.