Four new Pythium species from aquatic environments in Japan.

Four new species of Pythium s.str., namely Pythium utonaiense, Pythium brachiatum, Pythium biforme and Pythium junctum, were described based on their morphology and molecular phylogeny. These species were isolated from freshwater samples collected from aquatic environments (pond and lake) in Japan. They were identified as belonging to the genus Pythium s.str. by their morphology, such as filamentous hyphal inflated structures, and molecular phylogenetic analyses based on the internal transcribed spacer region of the ribosomal RNA gene and mitochondrial cytochrome c oxidase subunit 1 gene. The new species are compared to closely related Pythium species regarding their phylogenetic positions and morphological features.