Clypeococcum wedinii, a pyrenocarpous ascomycete growing on the lichen genus Bunodophoron in Chile and New Zealand, is described as new to science. It differs from other Clypeococcum species in the combination of the following characteristics: a conspicuous gall formation, scattered, loose to dense stromatic growths sometimes looking like a clypeus, an ascomatal wall composed of both textura intricata and angularis in surface view, a non-amyloid hymenium, an absence of ostiolar filaments, 8-spored asci, and 1-septate ascospores arranged biseriately in the ascus. An updated key to the species of the lichenicolous genus Clypeococcum is provided. lichen-dwelling fungi, Polycoccaceae, Southern Hemisphere, taxonomy