Heterodermia key
| Key adapted from Edwards & Purvis (2009). | ||
| 1. | Thallus lobes elongate, entangled, ascending, with long black marginal cilia; soredia absent or confined to a central furrow on the underside of the lobes | Heterodermia leucomela |
| Thallus lobes usually forming irregular rosettes, marginal cilia short or absent; lacking isidia, but soralia or lobules present | 2 | |
| 2. | Lower surface corticate, white to tan-coloured | Heterodermia speciosa |
| Lower surface non-corticate, with yellow spots or ochraceous arachnoid layer | 3 | |
| 3. | Upper cortex C–, K± yellow, KC–, Pd– | Heterodermia obscurata |
| Upper cortex C–, K+ yellow→red (crystals), KC+ red, Pd+ orange | Heterodermia propagulifera | |