Abstract
A new species of Pythiales: Pythium cedri, isolated from Cedrus deodara (Pinaceae) in Jiangsu Province of China is described and illustrated based on morphological characters and supported by molecular phylogenetic analyses using ITS+COI sequences. Pythium cedri belongs to Pythium clade D and is characterized by presence of hyphal swellings, toruloid sporangia, ornamented oogonia with blunt spines, monoclinous antheridia, plerotic or nearly plerotic oospores, and relatively slow growth (11–15 mm d–1). A key to accepted species of Pythium clade D is provided.