The genus Travassosius Khalil, 1922 (Nematoda, Trichostrongyloidea) in beaver, Castor spp.: a review and suggestion for speciation

Cameron's (1938. On the morphology and parasitic development of Travassosius rufus Khalil, 1922, a trichostrongyle parasite of the Canadian beaver (Castor canadensis canadensis). Libra Jubilar L. Travassos, Rio de Janeiro, pp. 103–106) synonomy of Travassosius americanus with Travassosius rufus is rejected on the basis of examination of paratype specimens, other specimens from Alberta, British Columbia, and Pennsylvania, and statistical analysis. It is suggested that T. americanus in beaver of North America, Castor canadensis, is the ancestral stock and that T. rufus has evolved following allopatric evolution of the beaver of Eurasia, Castor fiber.