Clapperton Ranch: Several very dry 15mm unidentified Umbilicaria sp. with pale tan, rugose underside, no rhizines...on east rock face at mod. elev. in sagebrush steppe yesterday Thompson River Valley Southern Interior BC Canada..have never seen before and would appreciate any help with ID. (have sample in fridge to spot test using dissection scope with K, KC, C, P...if those are of any use with?)

Thanks! Bruce....sorry, did not see your reply til now...the added pics of specimen's lower thallus surface show bit darker now it is dry. Now I know more about what it is not and something more of U. lambii

Interesting! You sure have spent some time with these wonderful critters. The lack of obvious rhizines is particularly curious....will see if I can measure and ck shape of the spores and get back to yoypu....appreciate your direction and these excellent articles exploring the vast depths of U.   

Chris