Visible initially as conspicuous mats of yellow-green felty mycelium on the surface of effete wood-inhabiting ascomycetes, from which conidiophores are formed, and later as scattered superficial rugose yellowish-brown ascostromata, with the superficial mycelium largely degraded. Anamorph: Helicosporium virescens. Conidiomata absent. Conidiophores 180-400 µm in length, 4-5 µm diam. at the base, dark brown and thick-walled, paler at the apex, erect, the upper part sterile. Conidiogenous cells hardly modified morphologically from lower cells of the conidiophore, proliferation absent or sympodial with 1(-3) fertile loci. Conidia formed from small lateral denticles, 1-2 µm diam., helically coiled 2-3 times in one plane with an overall diameter of 10-20 µm, with 4-6 indistinct septa, appearing hyaline individually but yellow-green in mass, smooth, thin-walled. Teleomorph: ascostromata 140-230 µm diam., perithecial, unilocular, globose to obpyriform with a constricted base, superficial, covered with a bright yellow-brown scurfy layer which often degenerates so that overmature ascostromata appear almost black, the periphysate ostiole minutely papillate and visible as a dark brown dot. Ascomatal wall composed of an outer layer of thin-walled yellow ± globose cells to ca 12 µm diam, rarely with a few short golden brown setae, a principal wall layer of thick-walled yellow-brown angular cells to 9 µm diam, and an inner layer of thin-walled hyaline flattened cells. Interascal tissue of very thin-walled and rather irregular cellular pseudoparaphyses with filaments to 2.5 µm diam., sometimes degenerating by maturity of the asci. Asci 72-83 x 9-11 µm, cylindric-clavate with the apical portion sometimes slightly attenuated, short-stalked, thick-walled when young, fairly thick-walled when mature, fissitunicate, the apex obtuse to rounded with an inconspicuous ocular chamber, 8-spored. Ascospores arranged fasciculately, 39-47 x 2.5-4 µm, fusiform to filiform, widest slightly above the midpoint and tapering smoothly to the acute apices, 7- to 10-septate, not constricted at the septa, the primary septum not distinguishable morphologically, often strongly guttulate, hyaline, smooth- and thin-walled, without a gelatinous sheath or appendages.