Septoria cornina  

Lesions to 5 (-7) mm in longest dimension, circular, angular or irregular, the upper surface with an olivaceous to dark brown central area, surrounded by a distinct, broad, reddish to black margin.
Anamorph: conidiomata pycnidia, immersed, globose to cupulate, brown to black, 80-100 µm diam., many formed in each lesion, dehiscence circular to irregular, epigenous. Conidiophores absent. Conidiogenous cells hyaline, cylindrical to ampulliform, 5-8 x 2.5-5 µm, formed from the inner cells of the conidiomatal wall. Conidia  28-45 x 2-3 µm [(23-) 32-90 (-110) x 2-4 (-5) µm fide Farr 1991], hyaline, 1- to 3-septate [1-9 (-10) septate fide Farr 1991], cylindrical but usually gradually tapering towards apex, falcate or lunate, the apex obtuse, the base truncate.
Teleomorph: not known.