We report the occurrence of the Amazonian hylid Boana alfaroi outside of Ecuador for
the first time. The locality (Assis Brasil, state of Acre) lies in northern Brazil,
approximately 1,280 km southeast from the easternmost records in Ecuador. Additionally,
we describe the vocalization of a male of B. alfaroi from the Brazilian population,
including a second type of note besides the advertisement note. Boana alfaroi may
occur across Amazonian lowland forests of Ecuador, northern Peru, and the Brazilian
states of Acre and Amazonas.