Harrahium halli (Harrah, 1922) — Type species

Type host. Greater yellowlegs, Tringa melanoleuca (Gmelin) (Syn. Totanus melanoleucus [Gmelin]) ( Charadriiformes: Scolopacidae)— McNeil et al. (1995, 1996).

Type locality. Raleigh, North Carolina, USA.

Additional hosts. Solitary sandpiper, Tringa solitaria Wilson ( Charadriiformes: Scolopacidae)— Yamaguti (1971); Eurasian coot, Fulica atra Linnaeus ( Gruiformes: Rallidae)—Cordero del Campillo et al. (1980).

Additional localities. Creston, Iowa, USA—Harrah (1922); Andalusia, Spain—Cordero del Campillo et al. (1980); Venezuela—McNeil et al. (1995, 1996).

Previously proposed synonym. Cyclocoelum (Cyclocoelum) halli Harrah, 1922 — Bashkirova (1950).

Remarks. Originally described as Cyclocoelum (Cyclocoelum) halli Harrah, 1922, this species was transferred to Harrahium by Witenberg (1926) as the type species of the genus. It was considered to be a synonym of Cyclocoelum brasilianum Stossich, 1902 (= Selfcoelum brasilianum [Stossich, 1902] n. comb.) by Joyeux & Baer (1927) and Dubois (1959), and of Haematotrephus lanceolatum (Wedl, 1858) by Macko & Feige (1960). This species has a pretesticular ovary (opposite the anterior testis) that forms a triangle with the testes (Haematotrephinae), the genital pore appears to be prepharyngeal and the vitelline fields are not confluent posteriorly, and we therefore support Yamaguti’s (1971) retention of Harrahium to receive H. halli . Rudimentary oral sucker present—Harrah (1922) and Bashkirova (1950).