Two new Pythium species from China based on the morphology and DNA sequence data

In an investigation of Pythium species in lawn grassland of south China, two new species, Pythium breve and P. baisense, were identified based on morphological characteristics and DNA sequence data. These two new species differ morphologically from the other Pythium species by the oogonia encompassed by many antheridia and with 1–3 antheridia on the wavy and curved stalks. Furthermore, P. baisense with complexly lobed antheridial stalks differs from P. breve with antheridial stalks entwining the hyphae nearby the oogonia with several turns. Results of phylogenetic analyses showed that these two new species were clearly separated from morphologically similar Pythium species based on the internal transcribed spacer region (ITS1, 5.8S, ITS2) and cytochrome c oxidase subunit I (COXI) gene sequences using maximum parsimony and Bayesian methods. These two new species are described and illustrated in detail.