Order: Ostropales Family: Porinaceae
Species: Porina borreri
Photos: On Sycamore. Ballyrisode, Co. Cork, SW Ireland.
Identification confirmed by John Douglass (photographs)
The cracked or continuous thallus is grey-brown, greenish-brown or dark olive-black with small black perithecia (<0.5mm), one third to half immersed. The involucrellum is purplish-brown or brown. Asci are 8-spored, spores colourless, 6-7(-8) septate, (23-)28-35(-40) x (3-)4.5-5(-5.5) Ám. Microscope photographs below.
Chemical reactions negative.
Found on the rough bark of Oak, Ash and Sycamore in old parks and woodlands and on the smooth bark of old Holly and Beech.
Similar: Porina aenea. Smaller perithecia, 3-septate spores