Bionectria ralfsii
Stromata erumpent through bark, bearing solitary or clustered perithecia, inconspicuous when bearing solitary perithecia.
Anamorph: conidiomata sporodochia, on a poorly developed developed erumpent stroma, pulvinate to somewhat funnel-shaped. Conidiophores penicillate to verticillate. Conidiogenous cells almost cylindrical, or slightly widening upwards, tapering in the upper third towards the apex, with a short collarette and conspicuous periclinal thickening. Conidia (7.5–) 11.5–13.5 (–18) × (5–) 6.5–7.5 μm, broadly ellipsoidal to lemon-shaped, olive-green, smooth, asymmetric, with a flat, slightly laterally displaced scar.
Teleomorph: ascomata perithecia, 300–400 μm high and 400–500 μm diam., broadly obovoid or subglobose, with a flat apex, mostly broader than wide, in dried condition frequently somewhat cupulate, light orange, rough to scaly or finely warted; scales generally slightly less intensely coloured. Peridium composed of and outer layer of globose to angular cells, and an inner layer of flattened thinner-walled cells. Asci 70–95 × 11–17 μm, clavate, the apex broadly rounded; apical ring not differentiated, 8-spored. Ascospores arranged biseriately, (14.5–) 17.5–19.5 (–23) × (5.5–) 6–7.5 (–8) μm, ellipsoidal to broadly ellipsoidal, equally two-celled, not constricted at the septum, smooth to finely roughened.
Description adapted from Schroers (2001).
Plurivorous, on bark of a broad range of broadleaved woody plants; most refquently recorded on Acer, Ulex and Ulmus.
Throughout GBI, common in S England and apparently rarer in N England and Scotland.