Vegetative hyphae inconspicuous.
Anamorph: not known.
Teleomorph: ascomata perithecial, with the base immersed in the host thallus or almost superficial, not causing obvious damage to the host tissues, scattered or weakly clustered; 60-65 µm diam., ± globose, black in external view, the ostiole minutely papillate. Ascomatal wall dark brownish-black, composed of 2-4 layers of ± angular cells to 8 µm diam., opaque, the pigment amorphous and largely obscuring the peridial cells. Interascal tissue sparse, with a few thin-walled hyphae ca 3 µm diam. interspersed with the asci, the ostiole lined with periphyses. Asci (29.5-) 34.5-41 x 10.3-11.1 µm, obclavate, sessile or very shortly stipitate, thick-walled in the upper part and fissitunicate, not staining in iodine, 8-spored. Ascospores arranged biseriately, 10.2-13.8 x 2.7-3.4 µm, cylindric-clavate, hardly constricted at the single slightly supramedian septum, the upper cell sometimes slightly wider, the apex obtuse and the base obtuse to acute, hyaline, smooth, without a gelatinous sheath.
On thalli of Bilimbia lobulata and B. sabuletorum, apparently biotrophic in nutrition.
Reported from VC45 Pembrokeshire, VC64 MW Yorkshire and VC77 Lanarkshire.