dibaeis 的鑑定

In the field several images came to my mind, trying to guess what would be the genus/species of this observation: The first thoughts were related with one of the first books I acquired about lichens - Lichen Flora of the Greater Sonoran Desert Region - where beautiful photos of Buellia species with inflated areolas appeared: Buellia bolacina, B. lepidastroidea, B. paniformis; After some species of Acarospora came to my mind, but I could not recall one with white areolas; then the same with Rhizocarpon ... At the end, I recognize that the most probable would be Toninia, but this time not T. aromatica, that appears to be to be the unique species of the genus that I can find here. So, let's wait for the micoscopy, hoping that not in the forthcoming ... years, unless a better proposal appears.
I know I have a photo of the habitat: a calcerous rock formation usually called as "lapiaz" (french word), to be upload latter.