A new parasitic conidial Hchenicolous fungus is described, forming stromatic conidiomata on the thalli of Usnea flammea from western Ireland and is named Zevadiaperoccidentalis J. C. DAVU) & D. Hawksw. gen. et spec. nov. It is characterised by conidiomata with a pellicular covering, enterogenous phialidic conidiogenesis and brown aseptate or 1-septate conidia. The symptoms and development are described and the relationships with other similar conidial fungi are discussed, including a key to these taxa. hyphomycete, Ireland, lichenicolous, new genus, new species, Usnea flammea, Zevadia peroccidentalis