Abstract
The redbelly toad Melanophryniscus pachyrhynus (Miranda-Ribeiro, 1920) is a poorly known toad belonging to the M. tumifrons group, which inhabits rocky open areas on top of hilly landscapes of the Uruguayan Savanna ecoregion in Uruguay and southern Brazil. In this study we describe the advertisement and release calls from a redbelly toad population from the central Rio Grande do Sul, southern Brazil, based on recordings obtained during the winter season of 2011. The advertisement call consists of a complex call with two segments, the first segment comprising a series of single, unpulsed notes, and the second comprising a multi-pulsed note (a trill) highly variable in duration. The mean dominant frequency of the call is 2668 ± 154 Hz (2261–2932 Hz) and mean call duration is 37.07 ± 23.97 s (6.64–75.20 s). This feature, however, is highly variable depending on the duration of the second segment, which may be notably longer compared to calls of other species of the genus Melanophryniscus. The release call was recorded during amplexus of up to four individuals. It consists of a short trill with a dominant frequency of approximately 2245 Hz, emitted as a series of five to six pulsed notes, each comprising five or six pulses. The advertisement call of Melanophryniscus pachyrhynus is compared with those of four other Melanophryniscus species, and the similarities in habitat requirements and in the temporal pattern of reproduction for species of the M. tumifrons group are discussed.
