New species of Xerocomus (Boletales) from the Guiana Shield, with notes on their mycorrhizal status and fruiting occurrence

Abstract

Xerocomus cyaneibrunnescens, Xerocomus potaroensis, and Xerocomus parvogracilis (Boletales, Basidiomycota) are described as new species from the Pakaraima Mountains of Guyana, in the central Guiana Shield region. These boletes occur in neotropical forests dominated by ectomycorrhizal (ECM) trees in the genus Dicymbe (Fabaceae subfam. Caesalpinioideae). Each species produced basidiomata during a multi-year plot survey, and each was confirmed as an ECM symbiont with one or more leguminous host plant species in Guyana.

• Basidiomycota
• Boletaceae
• Boletineae
• Caesalpinioideae
• ectomycorrhizal fungi
• Guyana

Acknowledgments

The authors thank the following for financial support: University of Guyana Sabbatical Leave grant to DRH, National Science Foundation DEB-0918591 and the National Geographic Society’s Committee for Research and Exploration to TWH, and NSF DEB-0918730 to RV.

Field assistance in Guyana was provided by M. Chin, P. Henkel, C. Andrew, V. Joseph, P. Joseph, F. Edmund and L. Edmund. Jessie Uehling provided the line drawings. Kelly Matsunaga provided SEM images. Research permits were granted by the Guyana Environmental Protection Agency. Roy Watling facilitated access to Corner’s type specimens at E and provided helpful discussions. The Instituto Nacional de Pesquisas da Amazonia provided access to Singer’s type specimens. This paper is No. 186 in the Smithsonian Institution’s Biological Diversity of the Guiana Shield Program publication series.