Falcaustra chabaudi sp. n. (Nematoda: Kathlaniidae) from the Western Lesser Siren, Siren intermedia nettingi Goin, 1942

Falcaustra chabaudi sp. n. is described from 7 males and 10 females collected from the large intestine of the western lesser siren, Siren intermedia nettingi, in southern Illinois. This species most closely resembles F. cryptobranchi (Walton, 1930) Freitas and Lent, 1941, from which it differs by the absence of grooves spiraling part-way around the head, in the conformation of the anterior esophageal bulb, and in having spicules 1.21 to 1.34 mm long. F. chabaudi is differentiated from F. catesbeianae Walton, 1929, the only species in Falcaustra reported from the genus Siren.