Key to the Butyriboletus species from China

1. Pileus surface pink, red, rose, grape red, or always red-tinted...........................................................................................................2

1. Pileus surface pale brown, brown, dark brown, and never red-tinted ................................................................................................8

2. Pileus tomentose.................................................................................................................................................................................3

2. Pileus glabrous, dry, or viscid when wet ............................................................................................................................................5

3. Pileus surface pale brown, brown to reddish brown................................................................................................ Bu. huangnianlaii

3. Pileus surface pink to purple, dull red, or pale red-orange to orangish yellow..................................................................................4

4. Pileus surface pink to dull red, or orangish yellow, hymenophore surface yellow to orange or orangish red or pinkish red.............. ....................................................................................................................................................................................... Bu. floridanus

4. Pileus surface purple red to pale red-orange, hymenophore surface bright yellow to pale yellow............................... Bu. sinoregius

5. Pileus surface red................................................................................................................................................................................6

5. Pileus surface pink-yellow or yellow-brown......................................................................................................................................7

6. Basidiome large, pileus 50–130 mm in diam, the reticulation on stipe surface often cracked into patchy scales.............. Bu. rubrus

6. Basidiome large, pileus 30–80 mm in diam, the reticulation on stipe surface never cracked into patchy scales ................ Bu. frostii

7. Pileus surface pink-yellow, stipe surface with yellow reticulation ............................................................................. Bu. roseoflavus

7. Pileus surface yellow-brown, stipe surface with pink to rose reticulation .............................................................. Bu. subsplendidus

8. Pileus surface always purple tinted ..................................................................................................................... Bu. pseudospeciosus

8. Pileus surface never purple tinted.......................................................................................................................................................9

9. Tube layer green tinted when mature ............................................................................................................................. Bu. sanicibus

9. Tube layer pale yellow, bright yellow to yellow, and never green tinted when mature ...................................................................10

10. Stipe thick at apex and swollen at the base ........................................................................................................................ Bu. yicibus

10. Stipe mostly equal ............................................................................................................................................................................11

11. Context white, changing blue when exposed ............................................................................................................. Bu. hainanensis

11. Context yellow, unchanging color when exposed ..................................................................................................... Bu. brunneoides