We report first record for the mayfly species Waynokiops dentatogriphus Hill, Pfeiffer & Jacobus 2010 from a wadeable stream in Missouri based on aquatic macroinvertebrate community samples collected during September 2021 from a reach of the Meramec River in Dent County in the Ozark Highlands Ecological Section of the state. Select physical and water quality characteristics from the reach are also provided.