During a survey of Phytophthora diversity in Panama, fast-growing oomycete isolates were obtained from naturally fallen leaves of an unidentified tree species in a tropical cloud forest. Phylogenetic analyses of sequences from the nuclear ITS, LSU and ß–tubulin loci and the mitochondrial cox1 and cox2 genes revealed they belong to a new species of a new genus, officially described here as Synchrospora gen. nov., which resided as a basal genus within the Peronosporaceae. The type species S. medusiformis has unique morphological characters. The sporangiophores show determinate growth, multifurcating at the end forming a stunted, candelabra-like apex from which multiple (8 to >100) long, curved pedicels are growing simultaneously in a medusa-like way. The caducous papillate sporangia mature and are shed synchronously. The breeding system is homothallic, hence more inbreeding than outcrossing, with smooth-walled oogonia, plerotic oospores and paragynous antheridia. Optimum and maximum temperatures for growth are 22.5 and 25–27.5 °C, consistent with its natural cloud forest habitat. It is concluded that S. medusiformis is adapted to a lifestyle as canopy-dwelling leaf pathogen in tropical cloud forests. More oomycete surveys in the canopies of tropical rainforests and cloud forests are needed to elucidate the diversity and role of oomycetes and, in particular, S. medusiformis and possibly other Synchrospora taxa in this as yet under-explored habitat.

During extensive surveys of Phytophthora diversity, 14 new species were detected in natural ecosystems in Chile, Louisiana, Sweden, Ukraine, Vietnam and Indonesia. Multigene phylogeny based on the nuclear LSU, rpl10, ITS, ßtub, enl, hsp90, tef-1α, ras-ypt1 and tigA and the mitochondrial cox1, nadh1 and rps10 gene sequences demonstrated that they belong to phylogenetic Clade 10 which is structured into three subclades. Subclades 10a and 10b comprise soil- and waterborne species with nonpapillate sporangia and variable breeding systems, including the known P. afrocarpa, P. gallica and P. intercalaris and the new P. ludoviciana, P. procera, P. pseudogallica, P. scandinavica, P. subarctica, P. tenuimura, P. tonkinensis and P. ukrainensis. In contrast, all species in Subclade 10c are airborne with papillate sporangia and homothallic breeding system, including the known P. boehmeriae, P. kernoviae and P. morindae and the new P. celebensis, P. chilensis, P. javanensis, P. multiglobulosa, P. pseudochilensis and P. pseudokernoviae. All new species differed from each other and from related species by a unique combination of morphological characters, the breeding system, cardinal temperatures and growth rates. The biogeography and evolutionary history of Clade 10 are discussed and the hypothesis put forward that the extant subclades originate from early divergences of pre-Gondwanan ancestors (>175 Mya) into water-/soilborne and airborne lineages which during their global spread experienced multiple allopatric and sympatric radiations.