Description. Non-lichenized but often forming thallus-like, whitish to greyish patches on the substrate. Prothallus sometimes present. Photobiont absent. Sexual morph:Ascomata apothecial, black, circular to irregular to almost stellate in outline, adnate, emarginate. Hymenium hyaline, gel I+ blue, KI+ blue. Epithecium olive-brown, K+ olivegreen. Hypothecium hyaline to pale yellowish. Asci ovoid to clavate, bitunicate, fssitunicate, without distinct stipe, I−, with KI+ ring-shaped structure in tholus, 4–8-spored. Ascospores hyaline, 1–5-septate. Asexual morph:Pycnidia black, semi immersed to immersed; conidia aseptate, bacilliform.
Notes. Naevia was resurrected for the distinct Arthonia pinastri clade detected by molecular analysis. Characters that distinguish Naevia from Arthonia s. str. include the lack of a photobiont and amyloid (I+ blue, KI+ blue) hymenium.