Order: Arthoniales Family: Arthoniaceae
Species: Arthonia ilicina
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 Ám.
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