A yellow to brown mycoparasite that infects boletes, covering the host with a powdery or crustose layer of yellow conidia and later producing brown, warted perithecia. Infections often distort or completely mummify the host fruitbody.

Early stage: Host surface becomes pale yellow, powdery. Texture soft, felted, easily rubbed off.
Mid stage: Yellow becomes deep golden, then orange‑brown. Surface thickens into a crust, often cracking.
Late stage (teleomorph): Numerous brown perithecia appear as tiny pimples. Host becomes hard, brittle, often unrecognisable.