U. macroisophaga Hannum & Wilson, 1934

Type host. Killdeer, Charadrius vociferus Linnaeus (Syn. Oxyechus vociferous [Linnaeus]) (Charadriifromes: Charadriidae).

Type locality. Loma Portal, California, USA.

Remarks. This species was considered to be a synonym of Cyclocoelum (H.) lanceolatum (Wedl, 1858) by Dubois (1959) and of U. pseudocotylea Witenberg, 1923 by Bashkirova (1950). It should be noted that although Hannum & Wilson (1934) gave the pharynx width as 143–171 (pharynx wider than oral sucker; ratio of the widths of the pharynx and oral sucker about 1:0.8) in the original description, as appears to be the case in their Fig. 1; however, Fig. 2 shows the oral sucker to be a little wider than the pharynx (about 230; ratio of the widths of the pharynx and oral sucker about 1:1.1). Rudimentary oral sucker present—Hannum & Wilson (1934).