Arthonia fuscopurpurea

Parasitic on the thallus of Peltigera hymenina, apparently uncommon and confined to upland Britain, few records from Ireland. See http://fungi.myspecies.info/all-fungi/arthonia-fuscopurpurea, https://www.britishlichensociety.org.uk/lichenicolous-fungi and https://www.britishlichensociety.org.uk/sites/default/files/Arthoniacea…