The rosy-billed pochard, Netta peposaca (Vieillot, 1816), is a migratory bird that inhabits wetlands which have the surface covered by abundant vegetation, but also being found in lagoons or rice plantations. One hundred sixty-nine rosy-billed pochards, N. peposaca, were examined for helminths in the Municipalities of Santa Vitória do Palmar and Jaguarão, State of Rio Grande do Sul, Brazil (wintering site) and Alvear, Corrientes Province, northern Argentina (nesting site). Samples were obtained in 2002 and 2004. Birds were frozen in dry ice after collection. During necropsy they were categorized according to sex and maturity, either adult or juvenile. The cestode Microsomacanthus hopkinsi (Schiller, 1951) Spasskaia, 1966 was found in the anterior portion of caeca. Prevalence was 60.9% and mean infection 42.9, while the intensity of infection was 1 to 418 helminths/ host. The high preva...

The coypu (Myocastor coypus Molina, 1782) has been reported as the definitive host of Hippocrepis fuelleborni in Argentina and Uruguay; and Hippocrepis myocastoris Babero, Cabello & Kinoed, 1979 in Chile. Specimens of M. coypus (n = 4) from the State of Rio Grande do Sul, in Brazil, were received from donations and necropsied in the laboratory. Digeneans were identified as H. fuelleborni due to the presence of ventral papillae, oblique testes and eggs with no polar filaments. The prevalence of H. fuelleborni was 25%, with a mean intensity of infection of 12 helminths/ host. The infection of M. coypus by H. fuelleborni probably occurred as a result of the ingestion of aquatic plants with metacercariae. This is the first report of H. fuelleborni parasitizing M. coypus in the State of Rio Grande do Sul, Brazil.