Rhizosphaera kalkhoffii  

Mycelium mostly immersed, brown.
Anamorph: conidiomata pycnidia, formed above stomata from a minute hypostroma, also with some rhizine-like hyphae below; 50-95 µm tall and 70-115 µm diam., rather irregular in shape, subglobose to pyriform, the upper part black and the lower part mid brown, thin-walled, the peridium composed of 1-2 layers of globose thick-walled cells to ca 8 µm diam., the ostiole irregular and opening widely. Conidiophores absent. Conidiogenous cells formed from the inner cells of the peridium, ampulliform, proliferating percurrently with periclinal thickening visible, collarettes very inconspicuous. Conidia not formed in chains, 5-10 x 3-5 µm, ellipsoidal to broadly cylindrical, hyaline, aseptate, smooth- and thin-walled, without an epispore, gelatinous sheath or appendages.
Teleomorph: not known.