Phytophthora borealis and Phytophthora riparia, new species in Phytophthora ITS Clade 6

Abstract

Phytophthora borealis and Phytophthora riparia, identified in recent Phytophthora surveys of forest streams in Oregon, California and Alaska, are described as new species in Phytophthora ITS Clade 6. They are similar in growth form and morphology to P. gonapodyides and are predominately sterile. They present unique DNA sequences, however, and differ in temperature/growth relations and geographic distribution.

Key words:

• aquatic fungi
• β-tubulin
• cytochrome oxidase
• forest streams

Acknowledgments

We thank the Oregon Department of Forestry and the USDA Forest Service, Pacific Southwest Experiment Station and Southwest Oregon Forest Insect and Disease Center, for participation in, and support of, this work, and Prof Dave Rizzo, UC Davis, for sharing isolates. Laura Sims performed the Bayesian analysis.