In 1971, W. A. Weber described Buellia saurina from aeolian sandstone in the Dinosaur National Monument in Utah, U.S.A. In his description, Weber mentioned several characters that are rather unusual for the genus Buellia, especially a lemon yellow thallus and a violet-brown hymenium. Careful re-examination of material at ASU and the holotype from COLO demonstrates that the species does not belong to Buellia, but needs to be transferred to Rhizocarpon. The bright yellow pigment is rhizocarpic acid, a substance not known from Buellia. The asci of the specimens belong to the Rhizocarpon-type. Although the young ascospores are two-celled, they frequently become irregularly muriform with age. The violet epihymenial pigment that can be identified as atra-red, is also unusual in Buellia and currently only known from the taxonomically isolated Buellia vilis Th. Fr. The new combination, Rhizocarpon saurinum (W. A. Weber) Bungartz, is made.