A tail of two assassins, the best of times in Proctacanthus robber fly distributions on a longitudinal gradient in the age of wisdom (Diptera: Asilidae)

The large bodied robber fly genus Proctacanthus includes many species from North America. One group, which includes the named species P. longus,  has several similar forms whose cumulative ranges extend from peninsular Florida to the Great Plains of Colorado in a narrow band. In this presentation I explore the changes in morphology that occur along this gradient, and propose changes to the taxonomy of this group.