Abrothallus bertianus  

Stroma consisting of a flat shield-like structure to ca 200 µm diam, composed of a single layer of thick-walled dark brown textura epidermoidea. Ascomata erumpent from the centre of the stromatic tissue, apothecial, shallowly domed to ± hemispherical, sometimes eventually becoming almost spherical, 100-180 µm diam and to 150 µm tall, very dark brown to black, sometimes with an inconspicuous brown pruinose appearance due to released ascospores on the surface of the ascoma, often appearing somewhat roughened when dry. Peridium composed of several layers of thick-walled and variably pigmented cells, varying from textura globulosa to textura epidermoidea. Interascal tissue composed of a dense palisade of hyaline branched and anastomosing gelatinized cellular pseudoparaphyses to ca 80 µm in length and 2-3 µm diam, with the apices sometimes slightly swollen. Asci 44-58 x 11-15.5 µm, clavate to cylindric-clavate, rather short-stalked, the apex obtuse to rounded, very thick-walled, especially towards the apex, fissitunicate but without a conspicuous ocular chamber, 8-spored. Ascospores arranged biseriately, 10.5-13.5 (-15) x 4.5-6 µm, clavate with a slightly supramedian septum, the upper cell rounded and the lower cell cylindric-ellipsoidal, golden brown, rather thick-walled, with a verrucose ornamentation formed from extruded pigment, without a gelatinous sheath or appendages.

Conidiomata developing in the surface layer of the host thallus, pycnidial, 60-90 µm diam, ± conical to pyriform, the ostiole conspicuous. Conidiomatal wall 2-3 cells thick, with an outer dark brown layer of textura epidermoidea which is covered in part with thick-walled hyphae. Conidiophores absent. Conidiogenous cells formed in a layer lining the entire inner wall, 4-4.5 x 3-3.5 µm, ampulliform, proliferating with 1-2 annellides often visible. Conidia 6-7.5 x 4-5 µm, initially turbinate but maturing to become bacilliform to cylindrical, the ends rounded and with a broad hilum, hyaline, aseptate, thin- and smooth-walled, without a gelatinous sheath or appendages.