Helminths of swallows of the mountains of Colorado, including Acuaria coloradensis n. sp. (Nematoda: Spirurata).

Thirty-three tree swallows, Iridoprocne bicolor, and 5 violet-green swallows, Tachycineta thalassina, from the eastern slope of the Rocky Mountains of northern Colorado were examined for helminths. Six species were found: Diplotriaena obtusa, Acuaria coloradensis n. sp. (Nematoda); Vitta magniuncinata, Angularella audubonensis (Cestoda); Plagiorchis maculosus (Trematoda); Mediorhynchus papillosus (Acanthocephala). The new species is most similar to A. multispinosa Perez Vigueras, 1937, but has 11 pairs of anal papillae and spicules measuring 125 micron and 140 micron.