Trematodes of the genus Pneumatophilus occur in the lungs and tracheae of snakes of North America. Pneumatophilus tracheophilus n. sp. is described from the eastern mud snake, Farancia abacura abacura, from Florida, U.S.A. The new species differs from previously known members of Pneumatophilus according to the following suite of characteristics: deeply lobate to dendritic testes that are longer than wide, ovary positioned more posteriorly (postacetabular) than in the specimens of other species, body that is oval, and host species. Three previously described species, Pneumatophilus variabilis, Pneumatophilus foliaformis, and Pneumatophilus leidyi, are reinstated, and a key to species of Pneumatophilus is included.