Release Call during Interspecific Amplexus in Boana raniceps (Cope, 1862): Evidence of Acoustic Variation from the Atlantic Forest of Northeast, Brazil

The genus Boana (Hylidae) comprises over 100 species distributed primarily across tropical regions of the Americas. While the advertisement calls of Boana raniceps are relatively well documented, information on its secondary vocalizations, such as the release call, remains scarce, particularly for populations in the Atlantic Forest. Addressing this gap, the present study provides the first description of the release call of B. raniceps recorded in an Atlantic Forest remnant in northeastern Brazil, during an interspecific amplexus attempt between males of Boana albomarginata and B. raniceps. The vocalization was recorded in the field using a digital recorder and directional microphone, and subsequently analyzed with Raven Pro 1.6 software. The observed release call exhibited a mean duration of 0.389 ± 0.08 s, with minimum, maximum, and dominant frequencies of 937.5 ± 35.84 Hz, 3656.25 ± 683.55 Hz, and 1593.75 ± 280.77 Hz, respectively, values notably higher than those previously reported for the species in the Cerrado biome, specifically in the state of Goiás. These differences suggest acoustic variation potentially driven by microevolutionary processes due to geographic isolation, resulting in population-specific adaptations to local environmental conditions. The vocalization was emitted as a reflexive response to the amplexus attempt by B. albomarginata, representing a novel behavioral record between males of these species. This description advances the understanding of secondary acoustic repertoires in B. raniceps and highlights their relevance for studies on acoustic communication, reproductive behavior, and taxonomic delimitation in Neotropical anurans.