During the course of a study on the endohelminth parasites of birds, specimens of an undescribed species of Tylodelphys Diesing, 1850 (Diplostomidae) were collected from the wood stork, Mycteria americana L., from Formosa Province, Argentina. Tylodelphys brevis sp. nov. can be distinguished from the other Neotropical species of this genus, T. elongata, T. americana and T. adulta, principally by the smaller size of the body (570–851 μm), by the fewer eggs in the uterus (1–2) and by the smaller ratio of body to egg length (6–8). This is the second report of an adult of the genus Tylodelphys from Argentina and the first record of a digenean species parasitizing Mycteria americana in this country.