The life history of the trematode Pygidiopsis macrostomum
Travassos, 1928 is described for the first time. Rediae and cercariae were obtained from naturally infected snails Heleobia australis
(d´Orbigny), a new first intermediate host. Metacercariae were found encysted in the mesenteries of three naturally infected guppies, Phalloptychus januarius
(Hensel), Jenynsia multidentata
(Jenyns) (new host records) and Poecilia vivipara
Bloch and Schneider. Experimental infections were successfully completed in the intermediate hosts H. australis and Poe. vivipara
reared in the laboratory and hamsters Mesocricetus auratus
Waterhouse were utilised as a definitive host.