Muellerella pygmaea
Muellerella pygmaea is a species of lichenicolous fungus in the family Verrucariaceae. It has a cosmopolitan distribution in Arctic-alpine areas and grows on the thallus and apothecia of a number of hosts.
Host species for Muellerella pygmaea include:Acarospora sp.Acarospora smaragdulaAspicilia calcareaCandelariella aurellaCarbonea assentiensLecanora alpigenaLecanora muralisLecanora polytropaLecidea grisellaLecidea lapicidaLecidea obluridataTephromela atraRhizocarpon geographicum