New species from Phytophthora Clade 6a: evidence for recent radiation

During routine vegetation health surveys in the southwest of Western Australia (SWWA), several Phytophthora isolates with affinity to Clade 6a have been recovered. In this study, all known species from Clade 6a, P. inundata, P. humicola, P. gemini, P. ‘walnut’ and P. ‘personii’, and the new isolates were compared based on morphology and DNA sequence data from three nuclear genes and two mitochondrial genes resulting in the description of five new species, P. balyanboodja, P. condilina, P. cooljarloo, P. kwongonina and P. pseudorosacearum. With the exception of P. gemini and P. humicola, all species from Clade 6a have been recovered from natural ecosystems in SWWA. These species are morphologically similar, with predominantly ovoid sporangia and nested and extended internal proliferation. If oospores are present, they tend to be aplerotic with paragynous antheridia mostly attached adjacent to the oogonial stalk. They can all grow at 35C and have a fast growth rate on most agar media. T...