Galls formed on thalli of Xanthoria parietina and X. calcicola. Galls often shaped like a three-cornered hat. Later becoming more irregular.
Anamorph: Conidiomata pycnidial, immersed in galled areas of the thallus, often interspersed with ascostromata, ± globose, 75-100 μm diam., wall pale, 8-12 μm thick, composed of 3-5 layers of polyhedral cells 5-10 μm diam. Conidiogenous cells ± ampulliform below, tapering to subcylindrical above, 7-10 x 1.5-2.5 μm. Conidia in short chains, non-septate, hyaline, cylindrical, ± compressed centrally, 3.5-5 x 1.5-2 μm.
Teleomorph: Ascostromata perithecia, immersed, subglobose below, tapering above, 150-200 μm wide, 150-250 μm tall; wall colourless but pale brown to dark brown around the ostiole, 20-30 μm thick, composed of polyhedral cells 5-10 μm diam., with elongate cells around ostiole. Periphyses hyaline, 2-2.5 μm wide. Paraphyses absent. Asci clavate, bitunicate, with distinct apical beak, 45-65 x 12-20 μm, 8-spored. Ascospores distichous, ellipsoid, aseptate, hyaline, usually with 2(-3) guttules, 15-20 x 4-7 μm.
The shape of the galls is characteristic. No other fungus growing on species of Xanthoria has pale-walled perithecia or pale-walled pycnidia.