Phytophthora versiformis sp. nov., a new species from Australia related to P. quercina

During routine surveys of Corymbia calophylla, a widespread tree currently experiencing decline over a large area of its native range of south west Western Australia, a slow growing Phytophthora species was often recovered from roots and rhizosphere soil. This species grew more slowly, produced a wide array of morphological features and was visibly different to all other Phytophthora species present in Western Australia. Phylogenetic analyses of the ITS, cox1, HSP90, β-tubulin and NADH gene regions confirmed this to be a new species closely related to P. quercina and the provisional species P. ‘ohioensis’. The new species is described here as Phytophthora versiformis sp. nov. It produces persistent, papillate sporangia of variable shape, oogonia with thick-walled oospores, and paragynous antheridia. To date this species has only been recovered from C. calophylla. Pathogenicity trials indicate that while P. versiformis can infect the roots of C. calophylla it does not lead to seedling death.