Order: Incertae sedis Family: Arthopyreniaceae
Species: Arthopyrenia salicis
Photos: On Ash and Sycamore. Co. Cork, SW Ireland.
Thallus +/- inconspicuous, pale to darker brown, sometimes pinkish when fresh. Not always lichenised, the Trentepholia cells in the thalli can be abundant or undetectable. Small pimple-like perithecia, the ostiole (pore-like opening) often +/- sunken. Spores colourless, 1-septate, 14-17 x 4-5.5 Ám. Cells constricted at septum, lower cell often with a median constriction. Micro photos below.
Chemical reactions negative.
Widespread throughout Ireland on smooth bark, especially Hazel.
Similar: Arthopyrenia punctiformis and A. nitescens
Mycomicrothelia confusa has brown spores.