|I’d Call It That||3.0||0.00||0|
sum(score * weight) /
(total weight + 1)
The only Pertusaria in the Sonoran Flora with well-formed disk-shaped apothecia on rocks is P. flavicunda, which is “endemic to western North America”. Hmmm. But there aren’t any rock-dwelling Ochrolechia in the same flora without the usual enormous apothecia. Wait, there are two additional brown-spored Pertusaria (sometimes placed in Megalaria apparently) with disk-shaped apothecia on rocks, but I haven’t seen photos of them: P. islandica and P. occidentalis. I agree with you that it doesn’t look like any Lecanora, at least.
Summary: I’m stumped! :)
Pertusaria and some of Lecanora as well. The first I eliminate because (at least the species I saw) either the margins of discs are more wrinkled or the thallus is more greenish. Similarly, I eliminate Lecanora because either they live on trees or the margins of the discs are more thin.
Do you have any particular species in mind?
(This is a beatiful specimen, indeed!)