Among bufonids, Rhinella stands out for its high diversity in larval morphology and ecomorphology, including for instance proverbial pond-type tadpoles (e.g., the R. marina group), generalized tadpoles from lotic systems (e.g., in the R. spinulosa group), and tadpoles that develop in phytotelmata (e.g., some species within the R. margaritifera group). The R. veraguensis group comprises highly specialized tadpoles with the abdominal wall modified into a sucker (R. chrysophora, R. quechua, and R. veraguensis), as well as forms that exhibit gular bulges likely representing an intermediate state toward the presence of an abdominal sucker (R. rumbolli). Given the generally conservative larval morphotypes within species groups in this and other bufonid genera, the discovery of tadpoles of R. justinianoi from a captive breeding population was surprising. Contrary to expectations, these are endotrophic nidicolous tadpoles that combine features typical of this developmental mode (e.g., mouthparts less developed than in related lotic tadpoles, large otic capsules) with traits characteristic of the R. veraguensis group (e.g., gular bulges, labial tooth row A2 not interrupted). In this work, we describe the external and skeletal anatomy of a small sample of tadpoles and discuss their relevance in the context of phylogeny, developmental modes, and larval ecomorphology in Rhinella. In addition, we briefly summarize the taxonomic distribution and morphological evolution of endotrophic larvae in Bufonidae.
Vera Candioti, F., Quinteros-Muñoz, O., Camacho-Badani, T., Baldo, D. and Pereyra, M.O. 2026. An unexpected tadpole: developmental mode and larval morphology of endotrophic Rhinella justinianoi (Anura: Bufonidae), with implications for bufonid larval ecomorphology and evolution. Zoologischer Anzeiger 323: 56–65.
 | Florencia Vera Candioti Investigadora Principal CONICET Herpetología |