Two new species, Phytopythium iriomotense sp. nov. and P. aichiense sp. nov., isolated from river water and water purification sludge in Japan

Phytopythium iriomotense sp. nov. was isolated from river water of Iriomote Island, Okinawa Prefecture, Japan. The species can grow at 10–35 °C. The optimum temperature was 30 °C, with a radial growth of 24.3 mm per day. The species is morphologically characterized by globose to sub-globose sporangia with apical papillae, internally nested and internally extended proliferating sporangia, lateral hyphal swellings, compound sympodia, globose and smooth oogonia, amphigynous or crook-necked antheridial cells, oogonia with double oospores, aplerotic or plerotic oospores, and a chrysanthemum growth pattern on V8A. Phytopythium aichiense sp. nov. was isolated from water purification sludge in Aichi prefecture, Japan. The species can grow at 3–35 °C. The optimum temperature was 28 °C with a radial growth of 12.3 mm per day. P. aichiense is morphologically characterized by sub-globose, ovoid or limoniform sporangia with apical papillae, internally nested or internally extended proliferating sporangia, filamentous inflated or crook-necked antheridial cells, aplerotic oospores and a stellate growth pattern on V8A. Phylogenetic analyses based on the rDNA ITS region and combined phylogenetic trees based on the nuclear LSU rDNA and beta-tubulin gene, and the mitochondrial coxI and coxII genes, revealed that both species are genetically distinct from each other and from morphologically related species.