Blarneya hibemica gen. et sp. nov. (Hyphomycetes, Moniliales) is described on the basis of three collections from southern Ireland. It colonizes thalli of Enterographa crassa.Lecanactis abietina and L. premnea, killing their fungal components, and taking over the Trentepohlia they contain for form its own lichenized thallus. Two characteristically lichen metabolites, lecanoric and schizopeltic acids, are formed by B. hibemica, the hyphae of which can become encrusted with crystals of these compounds. Conidiogenesis is holoblastic with conidia delimited by deposition of new wall layers. The occurrence of schizopeltic acid and the method of conidiogenesis suggest that B. hibemica is an imperfect state of a member of the Hysteriales. This is only the second report of a lichenized hvphomycete from Europe.