Mycosphaerellaceae Stigmidium congestum # Lichenicolous.Photographs on Lecanora chlarotera Parasitic in the apothecia of the Lecanora chlarotera group Small, black, subglobose perithecia are immersed in the host apothecia causing them to become completely blackened. Asci 8-spored, the spores hyaline, 1(-3) septate, (11-)12-14(-16) x (2.5-)3-4 µm with a finely verruculose epispore. Microscope photograph below. Similar: Stigmidium punctillum is found on Lecania species, the spores are 1-septate, 14-18 x 3.5-5 µm

Microscope photograph

Stigmidium congestum
Studland, Dorset. May 2015