Key to the worldwide species of Cotylidia s.l.

1. Producing hymenial cystidia, pileocystidia, and caulocystidia, growth on moss············2

1. Only producing hymenial cystidia, growth on soil or wood··············································5

2. Basidiospores with two guttules································································Cotylidia guttulata

2. Basidiospores without guttules······························································································3

3. Basidiospores > 5 µm in length·································································Cotylidia muscigena

3. Basidiospores < 5 µm in length·······························································································4

4. Pileus pale alutaceous brown; stipe lateral; basidiospores 3–3.75 × 1.2–2.5 µm·················

····························································································································Cotylidia carpatica

4. Pileus buff to brownish, darker in the center; stipe central to eccentric; basidiospores

4–5 × 2–2.5 µm···································································································Cotylidia undulata

5. Basidiomata growing on wood·······························································································6

5. Basidiomata growing on soil···································································································8

6. Basidiomata growing on burnt wood, with white basidiomata, small hymenial cystidia

(40–60 × 4–6 μm) and basidiospores (4–5 × 3–3.5 µm)································Cotylidia marsicana

6. Basidiomata most frequently growing on woody substrates, with bright yellow or white

basidiomata, large hymenial cystidia (up to 122 × 6–26 μm) and basidiospores (6.8–7.5 ×

3–3.75 µm)·····································································································································7

7. Pileus bright yellow··························································Cotylidia aurantiaca var. aurantiaca

7. Pileus white to cream··································································Cotylidia aurantiaca var. alba

8. Hymenial cystidia septate······································································Neocotylidia diaphana

8. Hymenial cystidia nonseptate·································································································9

9. Basidiomata more or less white to cream·············································································10

9. Basidiomata pinkish, purplish-red, or at least bright red-orange at the margin·············12

10. Growing on the ground under Pinus tabuliformis, hymenophore covered with distinct

white fibers, hymenial cystidia (70–115 × 12.5–20 µm), basidiospores (5–5.5 × 3–3.5 µm)····

····························································································································Neocotylidia fibrae

10. Not growing on the ground under Pinus tabuliformis, hymenophore without white

fibers··············································································································································11

11. Hymenial cystidia thick-walled, basidiospores large (7–9.3 × 3.2–4.4 µm)·························

···················································································································Neocotylidia bambusicola

11. Hymenial cystidia thin-walled, basidiospores small (6–8.5 × 2.5–3.5 µm)·························

··························································································································Cotylidia komabensis

12. Pileal surface bright red-orange at the margin (all basidiomata when young), large

hymenial cystidia (70–160 × 10–14 μm) and basidiospores (8–10 × 4–4.6 µm)·························

······························································································································Cotylidia pannosa

12. Pileus of dried material pinkish or purplish-red, small hymenial cystidia (up to 78 ×

7–9 μm) and basidiospores (6 × 3 µm)··························································Cotylidia harmandii