Microscoping differences of microalgae

NAKADA, TakashiLecturer

Phycology, Phylogenetics, Taxonomy, Evolutionary, biology, Morphology, Nomenclature
Taxonomic studies toward phylogenetic classification of microalgae
Culture strains
Molecular phylogeny
International Code of Nomenclature for algae, fungi, and plants

Worlds of micro-organisms are as far as space and deep-see for human beings. Various invisibly small organisms live in water, and many of them are new species or insufficiently studied.
Among such microbes, I focuses on Volvocales (Chlorophyceae). Volvocales includes algae with various morphology. Most live in freshwater, but some live in the sea or even in snow. Most are unicellular, but some colony-forming. They are the “museum of cellular evolution”, as they show various kinds of evolution at the cellular level.
However, there are many new species, species not known in Japan, species without recent records, even in neighboring ponds and soils. Their classification is also problematic.
Recently, molecular phylogenetic analyses revealed problems in traditional taxonomy and rebuilding new classification systems, but molecular sequence does not illustrate actual picture of each organism. Thus, we should cultivate and observe microalgae, and study even physiology of each species.
Uniting these knowledge, we can improve taxonomy of microalgae.
In this laboratory, morphology, cultivation, and physiology of Volvocales are studied.
– Establishing new strains, and describing new and poorly known species.
– Research on species differentiation.
– Examining less-used characteristics such as physiology.
– Reconstructing classification of Volvocales, satisfying both morphological and phylogenetical criteria.
I am also interested in the “names”, both scientific and Japanese names, and their nomenclature.


Microalgae are so diverse that there are many unknown species everywhere, even on our campus. Without understanding microalgal diversity, we cannot understand ecology of soils, ponds, rivers, the ocean, etc. I am especially interested in green algal taxonomy, and describing several new species using microscopy and phylogenetic analyses. I welcome any students interested in microalgae.


  • Nakada, T., Tsuchida, Y. & Tomita, M. Improved taxon sampling and multigene phylogeny of unicellular chlamydomonads closely related to the colonial volvocalean lineage Tetrabaenaceae-Goniaceae-Volvocaceae (Volvocales, Chlorophyceae). Mol. Phylogenet. Evol. 130, 1–8 (2019).
  • Nakada, T. & Tomita, M. Morphology and phylogeny of a new wall-less freshwater volvocalean flagellate, Hapalochloris nozakii gen. et sp. nov. (Volvocales, Chlorophyceae). J. Phycol. 53, 108–117 (2017).
  • Nakada, T., Tomita, M., Wu, J.-T. & Nozaki, H. Taxonomic revision of Chlamydomonas subg. Amphichloris (Volvocales, Chlorophyceae), with resurrection of the genus Dangeardinia and descriptions of Ixipapillifera gen. nov. and Rhysamphichloris gen. nov. J. Phycol. 52, 283–304 (2016).
  • Nakada, T., Misawa, K. & Nozaki, H. Molecular systematics of Volvocales (Chlorophyceae, Chlorophyta) based on exhaustive 18S rRNA phylogenetic analyses. Mol. Phylogenet. Evol. 48, 281–291 (2008).
  • Nakada, T., Nozaki, H. & Pröschold, T. Molecular phylogeny, ultrastructure and taxonomic revision of Chlorogonium (Chlorophyta): Emendation of Chlorogonium Ehrenberg and description of Gungnir gen. nov. and Rusalka gen. nov. J. Phycol. 44, 751–760 (2008).

Faculty of Science
Department of Biological Sciences

Grad School

Graduate School of Science
Department of Natural History Sciences
Biodiversity II

Contact Information

Faculty of Science, Building #5 5-609
Email: naktak [atmark] sci.hokudai.ac.jp

Teacher's Archive