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Family: AbrothallaceaeGenus: Abrothallus
Mycelium immersed, not staining in iodine. Stromata not observed.
Anamorph: conidiomata pycnidia, 120-240 µm diam. immersed at first but becoming erumpent through the surface of the host, about one third exposed at maturity, arising singly, scattered, sometimes arising on the site of a previous pycnidium and then assuming a rimmed appearance from above and a double-walled structure in vertical section, black, ostiolate, the ostiole often conspicuous. Conidiomatal wall 15-25 µm thick, thickest around the ostiole in the erumpent part of the pycnidium, dark brown, composed of thick-walled angular cells. Conidiophores absent. Conidiogenous cells lining the pycnidial cavity, 8-12 x 3-4 µm, ampulliform to lageniform, percurrently proliferating, annellate with to 4 annellations seen, hyaline, smooth-walled to weakly echinulate. Conidia collecting in a mucilaginous mass in the pycnidial cavity and extruded as a drop, (7-) 7.5-10.5 (-11.5) x (5-) 5.5-7 (-7.5) µm, obpyriform, the apex rounded, the base abruptly truncate, aseptate, hyaline, sometimes 1- to 3-guttulate, thin-walled, ± smooth at lower magnifications but with a widely spaced echinulate ornamentation just discernible by interference contrast.
Teleomorph: ascomata apothecia, erumpent through the host thallus, 400-600 µm diam. and 80-130 µm high, pulvinate, the upper surface flat to shallowly domed, in young specimens covered with a thick greenish pruina, older specimens dark brown to black. Epihymenium composed of dark brown granules. Hymenium pale brown to olivaceous, the pigmentation intensifying in K. Hypothecium pale brown, composed of angular cells covered with brown pigment. Interascal tissue of fairly thick-walled frequently branched hyaline paraphyses 2.5-3.5 µm diam., the apex rounded and sometimes slightly broadened. Asci 59-72 x 12.5-15.5 µm, clavate to cylindric-clavate, fairly short-stalked, the apex rounded, thick-walled and fissitunicate with rostrate dehiscence, with a pronounced apical cap and narrow ocular chamber, not staining in iodine, 8-spored. Ascospores 12–14 (–15) × (5–) 5.5–6.5 µm diam., rather variable in length/breadth ratio, 1-septate, the upper cell broader and ellipsoidal to cylindric-ellipsoidal, the lower cell cylindrical to conic-cylindrical and narrower, constricted slightly at the septum, the apex obtuse to rounded and the base acute to obtuse, dark brown, brown, thick-walled, strongly verrucose, without an epispore, gelatinous sheath or appendages.