Sphaerellothecium stereocaulorum  

Vegetative hyphae conspicuous, 4–8 μm diam., dark brown to blackish, moderately branched, usually superficial, sometimes immersed in the epinecral layer of the host thallus.
Anamorph: not known.
Teleomorph: ascomata perithecia, 20–50 μm diam., subglobose, black, glossy, ostiolate, immersed to semi-sessile on the host thallus, scattered, associated with dark hyphae. Peridium deep olive, 4–5 μm thick, of 1–2 layers of unevenly pigmented polyhedral cells 4–8 μm diam. Interascal tissue not seen. Asci (23–) 25–34 (–38) × (10–) 11–16 (–19), narrowly ovoid, sometimes narrowly ellipsoidal to ± cylindrical, ± sessile, fissitunicate, 8-spored. Ascospores irregularly arranged, (9–) 10–13 (–16) × 3–4.5 (–6) μm, narrowly soleiform, the lower cell narrower than the upper one and usually with an obtuse end, mostly 1-septate, occasionally 2–3-transseptate when old, not or slightly constricted at the septum, smooth or rarely seemingly verruculose when old, with oil droplets, mostly hyaline, without an epispore or gelatinous sheath.

GBI material is sterile and its identification is therefore tentative.