Key to the known corticolous species of Orcularia

1 Mature ascospores with isthmus between the apical lumina (bilocular) ...................................................................... 2

- Mature ascospores with apical and septal lumen (tetralocular).................................................................................... 3

2 Ascospores (11–)13–18(–22) × (6.5–)7–9(–10) µm ................................................................................... O. insperata

- Ascospores (10–)12–15(–16.5) × (5–)6–7.5(–8.5) µm ...................................................................................... O. elixii

3 Ascospores up to 20 µm long .......................................................................................................... O. placodiomorpha

- Ascospores more than 20 µm (up to 28 µm) long .................................................................... O. placodiomorphoides