<i>Arthonia epipolytropa</i> and <i>Arthonia subclemens</i>, two new lichenicolous species on <i>Lecanora polytropa</i>, with a key to the microfungi known on this common species

Abstract Arthonia epipolytropa Hafellner &amp; Grube and subclemens Hafellner, Muggia are described as new to science. Both specific parasites of Lecanora polytropa s. lat., but differing pathogenicity very different appearance. Whereas the clearly parasitic with its agglomerated ascomata is presently known certainty from a number localities along arch Alps (Austria, Italy, Switzerland), other parts Europe (Norway, Albania) northern America (USA), less harmful A . isolated sunken currently only small in Eastern Italy) various mountain ranges southern (Spain, North Macedonia, Greece). The species compared or one recently segregated genera. key fungi regularly found on lat. presented.