A homothallic semipapillate slow growing Phytophthora species associated with root rot of strawberries from greenhouse-grown plants in North Carolina, USA, root rot of roses in the Netherlands, and root rot of raspberry in Knoxfield, Australia, was identified. The main character of this organism is the production of paragynous antheridia with broad attachment to the oogonial wall. The morphology of the pathogen does not match that of any of the more than 85 described Phytophthora species. Phylogenetic analysis based on sequences of the internal transcribed spacer rDNA region (ITS1-5.8S-ITS2) of this taxon and those from other Phytophthora species from GenBank supports the conclusion that this organism is an unreported new species. In the phylogenetic tree with other reported Phytophthora species at the GenBank, the new species is more closely related to others in ITS clade 2 comprising semipapillate taxa including P. botryosa, P. citrophthora, P. colocasiae, P. meadii, P. citricola, P. inflata, P.tropicalis, P. capsici, Phytophthora sp. 'glovera' and P. multivesiculata. The most closely related species is P. multivesiculata isolated from Cymbidium orchid in the Netherlands. In this paper we describe the morphological characteristics and the phylogenetic relationships that support the description of this taxon as a new species Phytophthora bisheria sp. nov.