Setoseptoria arundinacea  

Anamorph: reported as Stagonospora vexata, but the connection has not been confirmed. Lucas (1968) found that the species produces ascomata and ascospores in culture, but no anamorph.
Teleomorph: ascostromata perithecial, 0.1-0.25 mm diam., globose to oblate, often elongated parallel to the long axis of the substratum, without a papilla, subcuticular, becoming ± superficial, gregarious, frequently forming raised longitudinally elongate groups, and then with a well-developed dark clypeus that is continuous between ascomata. Peridium 16-20 µm thick, glabrous, composed of compressed to polygonal cells, inwardly thicker and sometimes with elongate cells around the ostiole. Interascal tissue of numerous narrow cellular pseudoparaphyses ca 1.5 µm diam. Asci 60-100 x 13-16 µm, clavate, thick-walled and fissitunicate, 8-spored. Ascospores 26-34 x 4-5 µm, cylindrical-fusiform, hyaline and sometimes later brownish when over-mature, 1- to 3-septate, with the segment immediately above the primary septum slightly swollen, with a broad gelatinous sheath visible in some collections.