Melanophryniscus stelzneri (Redbelly Toad) and Leptodactylus mystacinus (Mustached Frog). Interspecific amplexus

Abstract

Most anurans can be classified as either explosive or prolonged breeders, although these actually represent two ends of a continuum. In general, anurans that inhabit arid or semiarid regions have explosive breeding periods due to the use of ephemeral ponds for reproduction. The genus Melanophryniscus is a putative monophyletic taxon currently represented by 20 species distributed in southern Brazil, southern Bolivia, Paraguay, Uruguay, and central and northern Argentina. Within the genus, M. stelzneri is an endemic species of Sierras Pampeanas from central-western Argentina Its reproduction is explosive and occurs in temporary ponds associated with heavy rains. When heavy rains and high temperatures occur, most species of anurans in the Chaco Serrano show explosive reproduction. This type of reproductive strategy can lead to atypical amplectic behavior including multiple amplexus, same-sex amplexus, and interspecific amplexus. In fact, within the genus Melanophryniscus some cases of atypical reproductive behavior are known, such as interspecific amplexus between different Melanophryniscus species reported by Baldo and Basso. Herein, we report two cases of atypical amplectic behavior in M. stelzneri: interspecific amplexus involving M. stelzneri and Leptodactylus mystacinus, and intraspecific amplexus between two male M. stelzneri.