Arthoniaceae Naevia punctiformis (Arthonia punctiformis) Growth type crustose Chemical results negative. Epithecium K+ pale green Often a pioneer species on twigs and small branches of trees and shrubs Immersed thallus, sometimes slightly bleaching the bark, photobiont absent. Small black apothecia, usually immersed and with a thin margin of bark cells. Spores 3(-5) septate, 13-23 x 5-7 µm, colourless, upper cell not enlarged. Pycnidia absent. Microscope photograph below. Often occurs with Arthopyrenia punctiformis. Similar: Arthonia radiata has a more conspicuous, lichenised thallus and the apothecia are often branched

Microscope photograph

Naevia punctiformis (Arthonia punctiformis)
On Ash branch. Holton Lee, Dorset and Wincombe Park, Wiltshire. February 2013 and May 2023