exciple: 15-30 µm thick Note: Unfortunately the Ochrolechia species on rocks have not been studied as carefully in North America as the ones on bark. Potentially what we are calling O. parella may prove to be a new species, and consequently it is designated as O.aff. parella. verruculae: thin at edge, becoming fairly thick conidia: bacilliform, straight 4.8-6 x <1 µm Notes: Apothecia of the southwestern North America population of O. pseudopallescens are more coarsely rugose-pruinose than those more eastern ones. All Sonoran material contains both protolichesterinic and lichesterinic acids (Brodo (1991).