Anamorph: "oblong" conidiomata producing conidia 3.5-5 x 0.5-1.5 µm were reported by Roux & Triebel (1994), but not found in other studies.
Teleomorph: stromata absent. Ascomata formed in groups of 20–30, primarily on the ascomata but also on thallus elements of the host lichen, 50–80 (–100) µm diam, perithecial, globose to subglobose, mostly superficial with only the base immersed, ostiolate, the ostiole minute and hardly protruding. Ascomatal wall 8–10 µm thick, thicker in the ostiolar region, composed of several layers of radially compressed textura angularis with cells 4–6 µm diam, less strongly pigmented in the outermost layer. Interascal tissue absent, with asci developing within a weakly or non-gelatinized hymenium that does not blue in iodine. Asci 32–38 × 13–16 µm, clavate to pyriform, thick-walled, the apex thickened with an inconspicuous ocular chamber and apparently with rostrate dehiscence, not blueing in iodine, 8-spored. Ascospores biseriately arranged, 10.5–12 (–14) × (3.5–) 4–5.5 µm, initially cylindrical to cylindric-clavate, the apex and base obtuse to rounded, hardly constricted at the median to marginally submedian septum, becoming wider and with the septum slightly more constricted after dehiscence, pale brown, smooth-walled, without a gelatinous sheath or appendages.
Not formally assessed; the known distribution is very scattered and it is likely that the species is much more common than the current map indicates.
On living thalli and especially apothecia of Xanthoria parietina. There are occasional reports of the species from other species of Xanthoria and also a few from Caloplaca species; these last probably need re-evaluation.
Reported from SW England and W and Central Wales, East Anglia and several widely scattered sites in Scotland. BLS map.