Order: Arthoniales       Family: Arthoniaceae Species: Arthonia varians Lichenicolous fungus. Photos: On Lecanora rupicola, Allihies, Co. Cork, SW Ireland. Small flat or slightly convex black apothecia develop in the hymenium of the host apothecia and eventually totally blacken the disc. The asci are 8-spored and the spores are usually 2-3 septate (rarely 1-septate), 11-17 × 5-6.5 µm. The epithecium is brown to olive-brown, K+ pale green. Micrographs below. Usually occurs in apothecia of Glaucomaria rupicola (Lecanora rupicola), occasional in apothecia of Lecanora helicopis. Similar: Arthonia apotheciorum has 1-septate spores and is parasitic on members of the Lecanora dispersa group.

Micrographs



Arthonia varians on Lecanora rupicola, March 2012. On Lecanora helicopis January 2012