Order: Incertae sedis Family: Arthopyreniaceae
Species: Arthopyrenia punctiformisGrowth type crustose
Photos: On Horse-chestnut twig. Ardsallagh, Co. Waterford, Ireland
The inconspicuous, non-lichenised thallus has small, +/- circular, clustered or scattered perithecia. Pycnidia are absent. Spores are initially colourless, 1-septate, 16-20(-22) x 4.5-5 Ám. Microscope photograph below.
Common as an early coloniser on smooth twigs and small branches of young trees and shrubs.