Anamorph: Conidiomata absent. Conidiophores developing from the surface tissues of young stromata, visible as yellowish green or grey effuse areas on decorticated wood, or small similarly coloured pustules on bark, rather ephemeral in nature. Conidiophores to 3 µm diam, indeterminate, decumbent to erect, initially hyaline but becoming brown and rough-walled, sympodially or dichotomously branched immediately below septa. Conidiogenous cells not differentiated morphologically from terminal conidiophore branches, rarely intercalary, nodose or irregular in form, proliferating sympodially and usually with between 4 and 8 conidial loci, clustered at the apex or extending over the top half of the cell, the loci with fairly conspicuous scars once the conidium has seceded. Conidia 5–9 × 2–4 µm, obovoid to cylindric-ellipsoidal, hyaline to pale brown, aseptate, smooth, with a minute truncate basal scar.
Teleomorph: Stromata 4–25 (–40) µm diam. and 2–7 µm thick, mounded or peltate, convex above and sometimes constricted at the base, often coalescing, irregular in form due to the conspicuous ascomatal mounds, brick red when young and darker and more purplish (often nearly black) when mature due to the farinose surface layer degenerating, with orange pigments diffusing into KOH that become dark brown on oxidation, and with yellow-orange crystalline deposits between the ascomata.. Ascomata 400–700 µm diam. and 500–700 µm high, ovoid to globose, developing above a conspicuous blackish basal layer, the ostioles conical and minutely papillate. Interascal tissue composed of simple unbranched filiform paraphyses to ca 3 µm diam. Asci 150–220 × 4.5–8 µm, the stalk 75–130 µm long, narrowly cylindrical, the apex rounded, thin-walled and not fissitunicate, not noticeably thicker-walled at the apex, with a doliiform to slightly funnel-shaped apical ring ca 1-2 µm in height and 2-2.5 µm diam. that blues in iodine, 8-spored. Ascospores 8.5–12 × 3.5–5.5 µm, fusiform-ellipsoidal, often inaequilateral but not laterally flattened, mid to dark brown, aseptate, with a straight dorsal longitudinal germ slit 50–75% of the spore length, a smooth epispore and a hyaline perispore that is thickened on the dorsal side and dehiscent in KOH.
Not formally assessed. In GB&I this is a common and widespread species, and would almost certainly be assessed as of Least Concern.
On dead, sometimes still attached branches. Particularly common on Betula species, but also found frequently on Alnus glutinosa, Corylus avellana, Fagus sylvatica and more rarely on other host plants. It has been demonstrated to be endophytic and is thus seen as an early colonizer.
Widespread in GB&I, recorded from all regions and climatic zones.