Parasitic on dying branches of Malus cf. domestica, causing canker of trees. Sexual morph: undetermined. Asexual morph: Conidiomata 950–1120 µm diam., 520–630 µm high, black, eustromatic, pycnidial, usually separate, immersed, conical, multilocular and convoluted, with locules 60–260 µm diam., 100–360 µm high, radiating and enlarging from the centre, separated by inner walls, but uniting in the ostiolar region, thick-walled, ostiolate, surrounded by yellow conidial mass at the tip. Ostiole 250–400 × 110–240 µm, single, circular, centrally located, prominent. Conidiomatal wall 10–250 µm thick, composed of thick-walled, pale brown to dark brown cells of textura angularis in the basal and lateral part, becoming thick-walled cells of textura intricata at the upper region. Conidophores arising from the inner wall layer of locular wall, hyaline, cylindrical to subcylindrical, branched repeatedly, smooth-walled. Conidogenous cells 8–15 × 2–3 µm, enteroblastic, phialidic, lageniform to subcylindrical, integrated or discrete, determinate, smooth-walled, with a minute collarette and narrow channel near apex. Conidia 4.8–7 × 1.3–2 µm ( = 5.7 × 1.8 µm; n = 30), hyaline, allantoid, unicellular, thin-walled, smooth-walled, eguttulate.
Material examined: Russia, Rostov Region, Shakhty City, near Grushevsky pond, grove of feral trees in gully, on dead and drying branches of Malus cf. domestica (Rosaceae), 18 May 2014, T. Bulgakov (MFLU 14–0788, holotype).
Cytospora parasitica (MFLU 14-0788, holotype) a Herbarium specimen. b Appearance of black conidiomata on the host. c Black conidioma with yellow conidia mass. d Vertical section of conidioma. e, g–i Sections of peridium (note e upper wall, h inner wall, g, i basal and lateral wall). f Ostiole. j–l Conidiophores, conidiogenous cells and developing conidia. m Conidia. Scale bars b–c, f = 200 µm, d = 500 µm, e, g = 100 µm, h = 50 µm, i = 20 µm, j–k, m = 10 µm, l = 5 µm.
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