Family: Unknown family Species: Phacothecium varium (Opegrapha physciaria) # Growth type lichenicolous Photos: On Xanthoria parietina. Co. Limerick, Ireland. The irregular black gall-like structures are initially immersed then become erumpent and occur singly or in clusters. They contain one to several apothecia and occasionally pycnidia. Asci are 8-spored, the spores 3-septate, 12-18 x 5-8 µm. Microscope photo below An infrequently recorded lichenicolous fungus that is parasitic on the thallus and apothecia of Xanthoria parietina Similar: Arthonia parietinaria forms clusters of much smaller apothecia on Xanthoria species. Spores 1-septate

Microscope photograph

Opegrapha physciaria #. September 2019