The stream tadpoles of Rhinella Rumbolli (Anura: Bufonidae)

Abstract

The Rhinella veraguensis group is likely a paraphyletic assemblage that contains 16 species of Andean toads. To date, descriptions are available for larval stages of only three species, all of which possess a distinct sucker in the abdominal region. In this study, we describe the tadpoles of Rhinella rumbolli, a medium-sized Salta Toad typical of forest streams in northwestern Argentina. Thirty-three larvae (Gosner Stages 32–36) were processed for studies of the external morphology, buccal cavity, and musculoskeletal system. These larvae show a mosaic of features, some typical of the genus and some others unique to the R. veraguensis group. Several character states are specific to R. rumbolli, namely the lack of an abdominal sucker, 2–4 lingual papillae, and the absence of adrostral cartilages. Some traits are frequent in other stream tadpoles such as the muscular tail, large oral disc with complete labial rows, and the wide and robust anterior neurocranium. Bufonid tadpoles exhibit an extraordinary variation in ecology, such as preferred microhabitat, and the diversity within the family is exemplified within the genus Rhinella. Further comparative morphological and developmental studies, framed in the context of phylogenetic hypotheses, are needed in order to explore the pattern variation in different clades and to discuss character evolution and form–function relationships.