Mycosphaerella equiseticola  

Anamorph: possibly Cladosporium macrocarpum agg.; conidiophores consistent with that morph description are closely associated and mostly erumpent through stomata in the material seen.
Teleomorph: ascomata immersed, developing in swarms within stomata, 70-100 µm diam., globose, black, the ostiole minutely papillate and not extending beoyond the substratum surface, fairly thin-walled. Interascal tissue not seen (possibly deliquescent at maturity). Asci 34-40 x 9.5-12 µm, pyriform, almost sessile or with a short broad stalk, the apex rounded, thick-walled and fissitunicate, 8-spored. Ascospores arranged biseriately, 11.3-13.2 x 2.5-3 µm, narrowly clavate, with a single ± median septum, hyaline, smooth, with a broad gelatinous sheath.