Cotylidia is a fungal genus characterized by small to moderately sized, white to palely yet brightly colored, stalked, fan-shaped to funnel-shaped fruit bodies with a smooth to wrinkled hymenium, tissues composed of monomitic hyphae, basidia producing smooth, nonamyloid spores, the absence of clamp connections, and bearing projecting cylindrical, thin-walled, hymenial cystidia. The genus is classified in the Hymenochaetales, however the type species, C. undulata has not yet been sequenced. Phylogenetically-related agaricoid fungi to the two species of Cotylidia thus far sequenced are in the genera Rickenella, Contumyces, Gyroflexus, Loreleia, Cantharellopsis and Blasiphalia, and Muscinupta and the clavarioid genus, Alloclavaria.