Order: Arthoniales       Family: Arthoniaceae Species: Arthonia ilicina Growth type crustose Photos: On Holly. Ballingeary, Co. Cork, SW Ireland. The immersed creamy-yellow thallus is usually surrounded by a brown prothallus. The dark-brown to blackish, irregularly shaped apothecia are 0.2-1mm in diameter, not pruinose. Asci 8-spored, spores becoming brown with age, 4-6 septate, 26-36 x 10-13 µm. Microscope photograph below. Chemical reactions negative. A species of oceanic woodlands. Occurs on smooth-barked trees in old, undisturbed woodland, mainly in the north and west of Ireland. Similar: A. ilicinella. Usually on Hazel, smaller discs 0.1-0.6mm diam

Microscope photograph

Arthonia ilicina. January 2011