Hypoderma rubi  

Zone lines thin, black, frequent.
Anamorph:  conidiomata preceding and accompanying the ascomata, 150–300 μm diam., black, shiny, circular, opening by one or two small central ostioles each about 10 μm diam.; subcuticular, with a blackened upper wall one cell thick, and a blackened lower wall two or three cells thick. Conidiogenous cells 7–11 × 1–2 μm, cylindrical to tapered, hyaline, smooth, proliferating sympodially. Conidia 2–4 × 1 μm, hyaline, aseptate, smooth.
Teleomorph: ascomata to 3 mm long, embedded in paler portions of otherwise browned stems, when dry black all over except for each end which is occasionally dark grey within the well defined perimeter line, elliptical to elongated elliptical, raising the substrate surface, opening by a single longitudinal split, lips present, grey; subcuticular, the clypeus well-developed and markedly thickened towards the lips, the lower wall blackened and joining the clypeus. Interascal tissue of filiform paraphyses, branched or unbranched, not swollen at the apex, about the same length as mature asci, enveloped in a mucous sheath. Asci 90–150 × 8–12 μm, clavate and long-stalked, thin-walled, not fissitunicate, not blueing in iodine, maturing sequentially, 8-spored. Ascospores biseriately arranged, 16–36 × 2·5–4 μm, elongated-clavate to cylindrical, often bent towards the top end, hyaline, aseptate, smooth, guttulate, without a gelatinous sheath.

Description adapted from Minter (1979).