Sphaeropsis foliicola

Species affecting living leaves of Crataegus sp., formerly classified as Sphaeropsis demersa var. foliicola, producing dark brown necrotic leaf spots with a blackish margin; in the center of these spots small black grain-like pycnidia appear.

Pycnidia with perithecioid grain-like structures, globose to slightly conical, 0.15 to 0.25 mm in diameter, housing the conidiogenous cells and conidia within.

Pycnidial wall composed of thick-walled intricate hyphae with short septa and copious brownish intracellular pigment.

Conidiogenous cells cylindrical, slightly conical to ampulliform (bottle-shaped), completely hyaline, short, 8 to 12 µm long and 3 to 5 µm wide at the base.

Conidia cylindrical-ellipsoidal to oblong, brownish under the microscope, smooth- and moderately thick-walled, 20 to 31 µm long and 11 to 15 µm wide.

Herbarium material available: JTP2513/25.