Order: Pyrenulales Family: Monoblastiaceae
Species: Acrocordia gemmata
Photos: On Sycamore. Ballyrisode, Co. Cork, SW Ireland.
Thin, cracked, white to light-grey thallus with large black perithecia, 0.5 to 1mm diameter. The ostiole is often off-centre and sometimes papillate. Scattered pycnidia. Asci usually 8-spored, spores 1(-3) septate, 15-27(-30) x 8-12 Ám. Micro photos below.
Chemical reactions negative.
Widespread on mature, rough-barked trees, especially Oak, Ash and Elm. Rare on Hazel.
Similar: Anisomeridium biforme. Smaller perithecia, to 0.5mm