Description: hallus inconspicuous, not lichenized, sometimes loosely associated with trentepohlioid algae. Perithecia dark brown to black, shiny, smooth, scattered singly, circular to slightly ellipsoid, c. 0.13-0.3 mm across, at first immersed, later becoming superficial, hemispherical to flattened, sometimes mammiform, the ostiole centrally located in a small papilla. Involucrellum dark brown to greenish-black, c. 15 μm thick, covering the exciple, sometimes extending in a basal fringe, composed of bark material intermixed with reddish-brown to greenish-black, smooth, thin-walled c. 3.5-5.5 μm thick hyphae slightly constricted at septa, forming a clypeate tissue; exciple colourless to greenish-black, c. 15 μm thick, slightly thicker at the angles of the perithecial cavity, intergrading with the involucrellum; consisting of colourless to greenish-black, thin-walled, isodiametric cells with an enlarged lumen, forming a textura angularis; pseudoparaphyses c. 2-2.5 μm thick; hymenial gel I+ yellowish. Asci 8-spored, cylindrical-clavate, 50-55 x 9-11 μm, bi- and fissitunicate, with a broad, truncate apical beak. Ascospores 1(-3)-septate, thread-like, arcuate or sigmoid, helically twisted, (25-)30-45 x 1.5-2.5 μm, attenuated at apices. Pycnidia black, shiny, circular to ellipsoid, scattered singly among the perithecia, 0.1-0.15 μm in diam., immersed to superficial, opening by a central ostiole, the wall dark brown to greenish-black. Microconidia hyaline, smooth, thin-walled, bacilliform, c. 3.75 x 1-1.5 μm; macroconidia 1-septate, hyaline, smooth, thin-walled, filiform, arcuate, c. 20-25 x 1-1.5 μm. Photobiont absent. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a southern temperate species found on the smooth bark of Carpinus, Corylus, more rarely of young Quercus (e.g. on twigs).