"Ulteramus republicensis" is known only from one fossil, the part side of the holotype, specimen number UWBM 77532, which is housed in the collections of the Burke Museum of Natural History in Seattle, Washington.The specimen is preserved as a compression fossil in silty yellow to grayish shale, which was recovered from outcrops of the Tom Thumb Tuff member of the Klondike Mountain Formation in 1993 by Wesley Wehr.