Researchers from Brazilian and international institutions have described a new frog species, Adenomera varcena, discovered in seasonally flooded várzea forests of western Acre, Brazil, near the Upper Juruá River. The find is notable because the genus Adenomera typically lives in dry forest habitats, making this the first known species from the group to inhabit Amazonian floodplains.
The frog looked so similar to closely related species that researchers could not tell it apart by appearance alone. The team, led by scientists from São Paulo State University (UNESP) and the Federal University of Minas Gerais (UFMG), confirmed it as a distinct species only by combining DNA analysis, recordings of its mating call, physical measurements, comparisons with museum specimens, and habitat data. The frog lacks a dark spot on the underside of its forearm, a trait separating it from its relatives, and its call is described as a short sound with a slow, distinctive rhythm.
The discovery, published in the journal Ichthyology & Herpetology, highlights how much cryptic diversity remains undocumented in the Amazon, where visually near-identical animals can turn out to be entirely separate species. Formally describing such species matters beyond taxonomy, as it underpins conservation priorities and legal protections for habitats that are increasingly threatened.