You can see them in the first two photos below the fruiting body. According to Mykoweb G. applanatum is especially common on Umbellularia californica in our area.

Perenniporia fraxinea is easy to tell apart from Ganoderma by its white spores, so checking the spores would be the first thing to do.

Perenniporia fraxinea is probably more common in the US than in Europe, where it’s reported from Aesculus, Castanea, Celtis, Eucalyptus, Fagus, Fraxinus, Gymnocladus, Juglans, Olea, Malus, Platanus, Populus, Prunus, Robinia, Quercus, Salix, Ulmus..