Key to Collybiopsis species in Thailand

1.a. Pileus whitish to cream ……………………………………………..................................................................................................2

b. Pileus other colors …………………………………………………. ................................................................................................3

2.a. Lateral stipe up to 15 mm long; pileus 15 mm in diameter, broadly convex becoming plano convex; basidiospores 5.5–9 × 3–4.5 μm........................................................................................................................................................................................... C. affixa

b. Central stipe 2–20 × 0.3–1 mm; pileus 2–20 mm in diameter, hemispherical; pileipellis rameales-structure; basidiospores 7.5–11 × 2.5–4.5 µm ..................................................................................................................................................................... C. ramealis

3.a. Pileus pale orange, grayish orange to reddish orange ……………… ...............................................................................................4

b. Pileus yellow-brown, pinkish brown, brown to dark brown ……….. ...............................................................................................6

4.a. Pileocystidia present; pileus 13–40 mm in diameter, plano-convex to concave-infundibuliform; pileipellis cutis; basidiospores 7–9 × 3–5 µm; cheilocystidia irregular cylindrical, lob ............................................................................................................. C. indocta

b. Pileocystidia absent ………………………………………………... ................................................................................................5

5.a. Pileus non-striate; stipe 38–46 × 2.5–4 mm; basidiospores 8–9.5 × 4–5 μm; cheilocystidia irregular cylindrical ........... C. gibbosa

b. Pileus rugulose-striate; stipe 21–38 × 1.5–2 mm; basidiospores 7–8.5 × 3.5–4.5 μm cheilocystidia clavate to fusiform .................. ........................................................................................................................................................................................ C. melanopus

6.a. Pileus ˃ 30 mm in diameter................................................................................................................................................................7

b. Pileus ≤ 30 mm in diameter................................................................................................................................................................8

7.a. Stipe 50–120 × 1.5–5 mm; basidiospores 6.5–8 × 3–4 µm; cheilocystidia cylindrical to clavate with coralloid projection; pleurocystidia absent ........................................................................................................................................................ C. confluens

b. Stipe 30–75 × 3–8 mm; basidiospores 8.5–10 × 3–4 µm; cheilocystidia narrowly clavate with apical, wart- or finger-like projections; pleurocystidia present........................................................................................................................................................ C. peronata

8.a. Stipe 40–47 × 1.5–2 mm; basidiospores 6–8 × 3–4 µm; pileipellis diverticulate; cheilocystidia 20–37.5 × 5–10 µm, subcylindrical, clavate, irregular; caulocystidia 47–80 × 4–7 µm, cylindrical, irregular ........................................................................ C. menehune

b. Stipe 18–25 × 2–3 mm; basidiospores 8–9 × 3–4 µm; pileipellis non-diverticulate; cheilocystidia 30–43 × 3–7 µm, clavate, flexuose, irregular; caulocystidia 27–37 × 4–7 µm, cylindrical to clavate, irregular........................................................ C. nonnulla