New hairworm (Nematomorpha, Gordiida) species described from the Arizona Madrean Sky Islands.

Gordiids, or freshwater hairworms, are members of the phylum Nematomorpha that use terrestrial definitive hosts (arthropods) and live as adults in rivers, lakes, or streams. The genus consists of 18 species, one of which was described from the Nearctic in 1851. More than 150 years later, we are describing a second species from a unique habitat within the Nearctic; the Madrean Sky Island complex.