The narratives of the conquest of Portuguese America used to inform about the main characteristics of the tropical nature and to describe the habits and customs of the Amerindian peoples. In particular, in the information about the Brazilian fauna there appeared the description of a hybrid being, both extraordinary and hostile, called Ipupiara. This monster was in fact a Tupi myth. However, the examination of texts on the Ipupiara allows to distinguish narrative patterns that are significant of different attitudes with regard to the Lusitan conquest. In most texts, the more involved the narrator was in the colonial project, the greater tendency he had to naturalize the Ipupiara, considering it a real inhabitant of the Brazilian rivers.As na...