I'm currently leading a community science project aimed at recording locations of sensitive epiphytic macrolichens on Mount Pisgah in Eugene. An additional outcome of the project has been a better documentation of saxicolous species that appear to be relatively uncommon in the Willamette Valley including Umbilicaria spp. Dermatocarpon spp., and Placynthium nigrum. While poking around some rock outcroppings recently, I found several thalli recently which macroscopically appear to be one of the Verrucaria species that is parasitic on Staurothele, but I wasn't able to find much documentation of Verrucaria in our region. Apologies if I'm off base here. This one (whatever it may be) is quite new to me.
Thanks, in advance, for any assistance!