Scinax exiguus was described from the Gran Sabana, southeastern Venezuela, and its distribution is associated with the one Amazonian savanna region in northern South America. Herein, we describe the aggressive call and redescribe the advertisement call of S. exiguus, including recordings from the type locality. Also, we report on intraspecific variation between Venezuelan and Brazilian populations and we make remarks on its distribution in Brazil. Advertisement calls from the type locality (Bolívar, Venezuela) mainly differ in temporal traits from those of the two Brazilian populations, especially in duration and pulse organization. In contrast, calls from both Brazilian populations had remarkable differences from each other in the dominant frequency. Body size also varied between the type series (Venezuela) and a Brazilian population. We suggest that the acoustic variation in S. exiguus might be explained partly by differences in temperature and varying degrees of motivational state of calling males. One of our study sites (Cantá, Roraima) now represents the southernmost record for the species in comparison to the previous record (Boa Vista). Additional research and conservation measures are required in the Guyanan savanna in northern South America for the protection of its endemics.