A key to worldwide species of Fibrodontia
1a. Hymenophore odontioid to hydnoid, aculei up to 1.5 mm long	2
b. Hymenophore grandinioid to odontioid, aculei up to 0.7 mm long	3
2a. Aculei usually less than 1 mm long, skeletal hyphae (2.5–)3.5–4.5 μm wide	F. gossypina
b. Aculei usually more than 1 mm long, skeletal hyphae 1.5–3.5 μm wide	F. subalba
3a. Basidiospores generally 7–9 μm long	F. tomentosa
b. Basidiospores generally 3.5–5.5 μm long	4
4a. Skeletal hyphae smooth	F. austrosinensis
b. Skeletal hyphae usually encrusted with crystals	5
5a. Basidiospores generally broadly ellipsoid to globose, 4.5–5 × 3.5–4.5 μm	F. brevidens
b. Basidiospores generally ellipsoid to ovoid, 3.5–4.5 × 2.5–3 μm	F. alba