Notes: Pyrenophora sieglingiae is closely related to Py. semeniperda and Py. wirreganensis. Morphologically, these species are similar, producing sterile ascomata with long necks. However, they can be distinguished by the size of their conidiophores (up to 700 μm in Py. sieglingiae vs. up to 180 μm in Py. semeniperda vs. up to 1 000 μm in Py. wirreganensis) and conidia [56–108(–120) × 15–23(–25.5) μm in Py. sieglingiae vs. 70–160 × 13–17 μm in Py. semeniperda vs. (30–)40–80(–100) × (10–)12–19(–22) μm in Py. wirreganensis). Moreover, Py. semeniperda produces conidia with more septa (up to 12 in Py. semeniperda vs. up to 8 in Py. sieglingiae vs. up to 9 in Py. wirreganensis), and it is the only one that produces a sexual morph. Pyrenophora sieglingiae has been isolated from Sieglingia from New Zealand while Py. wirreganensis occurs on Hordeum in Australia. Pyrenophora semeniperda has been isolated from both hosts in both locations, apart from other hosts that are widely distributed, i.e. Agropyron, Avena, Bromus, Cortaderia, Ehrhartia, Pennisetum and Triticum.