The diagnostic potential of dorsal and anal pterygiophore interdigitation patterns was examined in larval stages of Morone saxatilis, M. chrysops, M. americana and M.mississippiensis. The number and position of pterygiophores relative to interneural spaces 1-6 and 10-13 and interhaemal spaces 12-15 as well as total number of dorsal and anal pterygiophores are characters useful in delimiting larvae of American Morone species. Interdigitation patterns useful in separating M. mississippiensis and M. americana larvae were not found, however these two species may not co-occur
