Arthonia protoparmeliae
Anamorph: not known.
Teleomorph: ascomata in clusters but not confluent, 100-250 µm diam., ± globose, the upper part domed, shining black, at first immersed but becoming sessile or partially erumpent, the lower part cupulate and deeply immersed in the host thallus. Outer wall thin, dark brown, composed of hyphae similar to the interascal tissue, not staining in K or N. Hymenium ca 50 µm thick, subhyaline to orange-brown, I+ red, N-, K-, KI+ blue. Hypothecium 200-230 μm thick, dark brown. Interascal tissue of branched and anastomosing paraphyses 1.5-2 μm diam., the apical part not swollen or pigmented. Asci 37-42 x 10-14 μm, clavate, broadened at the apex, without a definite apical structure, 8-spored. Ascospores 12-14.5 x 4-5 μm, ellipsoidal, hyaline, 1-septate, with a narrow KI+ blue gelatinous sheath.
Not formally assessed, but only recorded on one occasion from GB&I.
On thalli of Protoparmelia badia.
In GB&I, reported from Unst (VC112 Shetland).