Rhizopogon togasawariana sp. nov., the first report of Rhizopogon associated with an Asian species of Pseudotsuga

Abstract

Rhizopogon subgenus Villosuli are the only members of the genus known to form an ectomycorrhizal relationship exclusively with Pseudotsuga. The specificity of this host relationship is unusual in that Rhizopogon is broadly associated with several tree genera within the Pinaceae and relationships with a host genus are typically distributed across Rhizopogon subgenera. Naturally occurring specimens of R. subg. Villosuli have been described only from North American collections, and the unique host relationship with Pseudotsuga is demonstrated only for Rhizopogon associated with P. menziesii (Douglas-fir), the dominant species of Pseudotsuga in North America. Species of Pseudotsuga are naturally distributed around the northern Pacific Rim, and Rhizopogon associates of other Pseudotsuga spp. are not yet described. Here we present the results of field sampling conducted in P. japonica forests throughout the Japanese archipelago and describe Rhizopogon togasawariana sp. nov., which occurs in ectomycorrhizal association with P. japonica. Placement of this new species within R. subg. Villosuli is supported by morphological and molecular phylogenetic analysis, and its implications to Pseudotsuga-Rhizopogon biogeography are discussed.

• biogeography
• ectomycorrhizae
• hypogeous
• Japan
• Rhizopogon subgenus Villosuli
• truffle

Acknowledgments

Field collections in Japan were conducted with the valuable assistance and guidance of Dr Nobuyuki Tanaka at the Kochi Prefectural Makino Botanical Garden Herbarium and Dr Masakuni Kimura at the Museum of Forests and Headwaters, Kawakami. K. Nishibori, M. Otsuka, K. Uno, Y. Hirayama and S. Vandruff provided laboratory assistance.

This work was supported by the National Science Foundation and the Japan Society for the Promotion of Science through an East Asia and Pacific Summer Institutes Fellowship (NSF award No. 1015355) to Alija Bajro Mujic.