S. lahillei (Dollfus, 1948) n. comb.

Type host. Red-gartered coot, Fulica armillata Vieillot (Gruiformes: Rallidae).

Type locality. Parana Delta, Parana River, Argentina—Thatcher (1993).

Remarks. Lahille (1918) considered this species to be C. mutabile (Zeder, 1800) and provided a minimal illustration but did not describe this species beyond a body length and individual egg size. Dollfus (1948) also did not describe this species, but renamed Monostoma mutabile of Lahille (1918) as Cyclocoelum lahillei (Dollfus, 1948) distinguishing it from C. mutabile based on the “grandes dimensions” of the pharynx and the postpharyngeal placement of the genital pore in C. lahillei. Dubois (1959) considered C. lahillei to be a synonym of C. mutabile. This species has a postpharyngeal genital pore and the vitelline fields are not confluent posteriorly, placing it in Selfcoelum. The anterior end of the specimen illustrated in Fig. 1 of the original description by Lahille (1918) appears to show the placement of the pharynx immediately above the intestinal bifurcation and an unusually short esophagus, suggesting that the anterior end is quite contracted, whereas in less contracted specimens, the genital pore likely would appear more posterior relative to the mid-level of the pharynx. No oral or ventral sucker described—Lahille (1918).