Yes, I also first thought there were no lichens in PF and I almost started a thread in Dave's Garden to suggest to allow them until I discovered that there were a couple, the same counts for mosses..
I have collected quite a lot of pics over the years of lichens and mosses I would like to add to PF. They fascinate me with their beauty and endless variety. I'm gradually trying to ID them with the help of some books I have and the internet. I realise though that some will be impossible to ID correctly as one needs a microscope for that and is really for specialists which I'm not.
The biggest problem though is to find out the Family name as it's not mentioned in my books and hard to find on Internet.
Thanks for finding the Family name of the Xanthoria