Description: Thallus inapparent, not lichenized, developing on cork wings of Acer campestre. Perithecia black, shiny, half-immersed, (0.1-)0.14-0.2(-0.24) mm across, smooth, scattered singly, subglobose to hemispherical, circular from above, often collapsed and then appearing cupulate, with a central apical papilla. Exciple continuous, of a textura angularis, composed of an outer dark brown, 12–24 μm thick layer of thin-walled cells with dark brown walls, and an inner, 12–16 μm thick hyaline to pale brown layer of (sub)hyaline cells. Paraphyses hyaline, smooth, thin-walled, septate, occasionally branched, 2-3 μm wide, embedded in a gelatinous matrix reacting I-; periphyses not observed. Asci 8-spored, cylindrical,, thin-walled. Ascospores 1-celled, hyaline, falcate, (21-)24-30(-32) x (2.5-)2.8-3.2(-3.5) μm, thin-walled, with subacute, tapering ends, often minutely guttulate. Pycnidia scattered, black, slightly smaller than perithecia. Conidia 1-celled, hyaline, falcate, (23-)26-29(-32) x (1.9-)2.0-2.4(-2.7) μm, often guttulate. Photobiont absent. Spot tests: all negative. Chemistry: without lichen substances.
Note: on cork wings and outgrowths (rhytidome) of living or dead branches of Acer campestre, known from Austria, Croatia and Germany, to be looked for in Italy.