Tying up loose threads: revised taxonomy and phylogeny of an avian-dispersed Neotropical rhizomorph-forming fungus

Abstract

Rhizomorpha corynecarpos Kunze was originally described from wet forests in Suriname. This unusual fungus forms white, sterile rhizomorphs bearing abundant club-shaped branches. Its evolutionary origins are unknown because reproductive structures have never been found. Recent collections and observations of R. corynecarpos were made from Belize, Brazil, Ecuador, Guyana, and Peru. Phylogenetic analyses of three nuclear rDNA regions (internal transcribed spacer, large ribosomal subunit, and small ribosomal subunit) were conducted to resolve the phylogenetic relationship of R. corynecarpos. Results show that this fungus is sister to Brunneocorticium bisporum—a widely distributed, tropical crust fungus. These two taxa along with Neocampanella blastanos form a clade within the primarily mushroom-forming Marasmiaceae. Based on phylogenetic evidence and micromorphological similarities, we propose the new combination, Brunneocorticium corynecarpon, to accommodate this species. Brunneocorticium corynecarpon is a pathogen, infecting the crowns of trees and shrubs in the Neotropics; the long, dangling rhizomorphs with lateral prongs probably colonize neighboring trees. Longer-distance dispersal can be accomplished by birds as it is used as construction material in nests of various avian species.