Xanthoriicola physciae (Kalchbr.) Sacc.
Conicosporium physciaea (Kalchbr.) Sacc.
Imperfect fungus, lichenicholous but not lichenified.
Initially forms brown-dark spots on apothecia, spots then grow and become confluent. Apothecia turn powdery blackish (as their close environment due to conidia projection). Conidia spherical, minutely echinulated, 3,5-6 µm diam.. Parasite of Xanthoria, notably in the coastal zone, here on Xanthoria aureola developing on rocks near the sea shore, and even more frequently on Xanthoria parietina on bark. The infected lichens are gradually destroyed from their center. Rather common in the most Western part of Brittany as long as searched specifically on its hosts.*