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. Occurs in apothecia of Glaucomaria rupicola (Lecanora rupicola). Similar: Arthonia apotheciorum has 1-septate spores and is parasitic on members of the Lecanora dispersa group.

Arthonia varians on Lecanora rupicola. March 2012