A reassessment of the vocalizations of three species of Ololygon (Anura: Hylidae) from southeastern Brazil

Abstract

The vocalizations of Ololygon hiemalis, O. ranki, and O. canastrensis are redescribed to provide further details on their complex vocal repertoires. The acoustic diagnosis of O. hiemalis is updated in relation to congeners, especially with respect to the morphologically similar O. ranki, for which we also evaluate the morphological diagnosis of both species. Three distinct types of notes are recognized in the vocalization of the three species (short squawk-like, long squawk-like and click-like), which are emitted in distinct acoustic organizations. The main organization of the three species is herein referred as the call Type “A”, each of which has a multi-note structure composed of a series of short squawk-like notes with note-by-note increase in amplitude along call duration. The call Type A of O. hiemalis was not described in the species original description. That of topotypes of O. ranki structurally resembles the call described in the original species description. Likewise, The call Type A of O. canastrensis matches that described in the original species description. Although O. hiemalis and O. ranki are phenotypically indistinguishable, there are quantitative differences in some call traits. Many species of Ololygon have complex vocalizations consisting of, at least, two types of notes, which can be emitted in different combinations. Despite the complexity of acoustic emissions, the call Type A of many species seems to be phylogenetically conserved. Because calls sometimes are only briefly described, we emphasize the need for, and importance of, comprehensive characterizations of anuran vocalizations to support future acoustic comparisons