Clavulicium macounii is a corticioid basidiomycete fungus in the family Hydnodontaceae, forming thin, resupinate (crust-like) fruiting bodies on decaying wood in temperate forests of North America. Named for Canadian botanist John Macoun, the species was described from specimens collected in Canada. Resupinate fungi like Clavulicium macounii grow tightly appressed to the substrate, lacking a distinct cap, and are often pale, waxy, or merulioid in texture. They play vital ecological roles as wood decomposers, contributing to nutrient cycling and the creation of habitat for forest invertebrates and cavity-nesting animals. Clavulicium macounii is saprotrophic, breaking down cellulose and lignin in dead hardwood and conifer logs and branches. The species is found in moist coniferous and mixed forests, often under bark or on shaded portions of logs. Corticioid fungi are a polyphyletic assemblage of wood-inhabiting species that are taxonomically diverse and often inconspicuous, making surveys of these organisms challenging. Species distributions and population sizes are poorly known compared to macrofungi with visible fruiting bodies. Conservation status has not been formally assessed; preservation of old-growth forest habitats with coarse woody debris is considered critical for maintaining populations of specialist wood-decay fungi.