Key to the species of Korean Myelochroa

1. Thallus isidiate∙∙∙∙∙∙ M. perisidians (Nyl.) Elix & Hale

1. Thallus without isidia ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ 2

2. Thallus sorediate or pustulate ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ 3

2. Thallus without soredia or pustules∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ 6

3. Pustules never forming soredia ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ 4

3. Pustules turning into soredia; soredia farinose∙∙∙∙∙∙∙∙∙ 5

4. Medulla P+ brick red, containing galbinic acid; moniliform cells present in the medulla∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ M. hayachinensis (Kurok.) Elix & Hale

4. Medulla P -, lacking galbinic acid; moniliform cells absent in the medulla ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ M. leucotyliza (Nyl.) Elix & Hale

5. Medulla P+ brick red, containing galbinic acid; moniliform cells present in the medulla∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ M. metarevoluta (Asahina) Elix & Hale

5. Medulla P -, lacking galbinic acid; moniliform cells absent in the medulla ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ M. aurulenta (Tuck.) Elix & Hale

6. Upper surface distinctly rugose, often bursting open along the ridges of wrinkles; upper cortex fragile and easily flaking away, exposing medulla ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ M. entotheiochroa (Hue) Elix & Hale

6. Upper surface smooth, cortex almost entire ∙∙∙∙∙∙∙∙∙∙∙∙ 7

7. Thallus rather tightly adnate; medulla P+ brick red, containing galbinic acid; moniliform cells present in the medulla∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ M. galbina (Ach.) Elix & Hale

7. Thallus adnate; medulla P - or P+ yellow, lacking galbinic acid; moniliform cells absent in the medulla∙∙ ∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙∙ M. irrugans (Nyl.) Elix & Hale