Stromata developing on the surface of the host thallus, 1.2-2 (-2.5) mm diam, round or somewhat irregular in outline, shallowly convex, irregular especially when overgrowing isidia, the surface matt black, ± bullate.
Anamorph: conidiomata pycnidia, immersed in the stroma and ± contemporaneous with the ascomata, 120-180 µm diam., ± globose, with a ± elongate neck. Conidiophores absent or short and unbranched, the conidiogenous cells forming in a palisade lining the conidiomatal wall. Conidiogenous cells 5-7 x 2-2.5 µm, conic-cylindrical, proliferating percurrently. Conidia 3-4 x ca 1 µm, bacillar to obovoid, aseptate, hyaline, thin-walled.
Teleomorph: ascomata perithecial, with 5-12 1ocules immersed in each stroma; 150-200 µm diam., with an elongate ostiolar canal 70-100 µm in length extending to the stroma surface, the locule walls not differentiated, the cells similar in structure to those of the stromatal tissue. Interascal tissue well-developed, composed of thin-walled branched cellular pseudoparaphyses 1.5-2 µm diam. Asci 80-100 x 18-22 µm, clavate, thick-walled and fissitunicate, the base tapered and the apex rounded, with an indistinct ocular chamber, not staining in iodine, 8-spored. Ascospores arranged obliquely uniseriately to biseriately, 18-22.5 x 5.5-8 µm, clavate to fusiform-ellipsoidal, often curved, 3- septa. slightly constricted at the median septum and with the outer septa sometimes oblique, dark brown, thick- and smooth-walled, without an epispore or gelatinous sheath.
Asssessed by Woods & Coppins (2012) as of Least Concern.
On living and moribund thalli of Parmelia species, most frequently found on P. saxatilis but also occasionally on P. omphalodes and P. sulcata.
Widespread in Scotland and upland areas of Wales and SW England, also in the New Forest. BLS map here.