Anamorph: conidiomata acervular, subcuticular, separate or confluent, formed of pale brown to hyaline thin-walled angular cells, the host cuticle discoloured. Conidiophores absent. Conidiogenous cells arising from the upper cells of the angular cells of the lower wall,
7-12 x 2-3 µm, flask-shaped to near-cylindrical, hyaline, smooth, proliferating percurrently, collarette and periclinal thickening inconspicuous. Conidia 5-9 x 2-2.5 µm, fusiform, straight, hyaline, thin-walled, smooth, without guttules.
Teleomorph: stromata 0.5-1 mm diam., discoid, flat, visible on both sides of the host leaf, only the outer layers melanized, gregarious, containing 1-3(-6) perithecia. Ascomata perithecia, 200-300 µm diam., 100-150 µm high; neck lateral, initially papilliform and scarcely emerging beyond the level of the substrate but later reaching a maximum height of 120 µm. Peridium 8-13 µm thick, composed of 3-4 layers of dark-walled angular cells. Interascal tissue absent. Asci produced horizontally within the perithecium, 130-150 x 5.5-8 µm, cylindrical with a rounded apex, tapering at the base, apically somewhat thick-walled, with a single discernable wall, with a I- refractive apical ring, 8-spored. Ascospores often lying in a twisted fascicle within the ascus, 122-142 x 1.5 µm, filiform, tapering towards the ends, hyaline, smooth, thin-walled, 3- to 5-septate, not constricted at the septa, without a gelatinous sheath or appendages.
Not formally assessed. There are relatively few records of the species in FRDBI, but it is inconspicuous and almost certainly under-reported despite its being implicated in plant disease. The species should probably be considered to be Data Deficient.
Distinguished from Linospora capreae and L. vulgaris (both species on Salix rather than Populus) by the presence of an anamorphic stage, stromata often containing more than one ascoma and ascospores with fewer septa and which lack appendages.
Reported from leaves of Populus nigra and P. tremula. Reports on Fraxinus excelsior need confirmation.
Scattered throughout England with a range extending from Surrey to Durham, and recorded from both ROI and Northern Ireland.
Probably initially endophytic, producing the anamorph in summer and autumn in large necrotic patches on leaves, and the teleomorph on rotten overwintered leaves the following spring.