Carcinomyces mycetophilus is a species of fungus in the class Tremellomycetes.

It is a parasite, producing extensive, gelatinous galls on basidiocarps (fruit bodies) of its host, the agaric Gymnopus dryophilus.

[1][2] Its generic placement is currently uncertain,[3] but morphologically it is close to the type species of Carcinomyces.

[1] It was first described by Charles Horton Peck from North America, where it is widespread and called Collybia jelly.

It has also been recorded in continental Europe.