Pythium rishiriense sp. nov. from water and P. alternatum sp. nov. from soil, two new species from Japan

FEMS Microbiol Lett. 2015 Jul;362(13):fnv086. doi: 10.1093/femsle/fnv086. Epub 2015 Jun 9.


In an investigation of Pythium species in natural ecosystems of Rishiri Island in Northern Japan, two new species, Pythium rishiriense and P. alternatum, were identified based on morphological and molecular analyses. Pythium rishiriense differed morphologically from other Pythium species by its characteristic oogonial formation which occasionally arranged in chains. Pythium alternatum differed morphologically from other Pythium species by its distinguishing sexual organs where oogonia occasionally arranged alternately with antheridia in chains. Pythium rishiriense is a fast growing, high-temperature loving species, while P. alternatum is a slow growing species. Phylogenetic analyses based on the internal transcribed spacer region and cytochrome c oxidase 1 gene sequences showed that these two species are clearly separate from morphologically similar species.

Keywords: high-temperature loving; identification; molecular phylogeny; morphology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • DNA, Ribosomal / genetics
  • DNA, Ribosomal Spacer / genetics
  • Hot Temperature
  • Japan
  • Phylogeny
  • Pythium / classification*
  • Pythium / genetics
  • Pythium / isolation & purification*
  • Pythium / ultrastructure
  • Sequence Alignment
  • Sequence Analysis, DNA
  • Soil / parasitology*
  • Water / parasitology*


  • DNA, Ribosomal
  • DNA, Ribosomal Spacer
  • Soil
  • Water