The remarkable larval morphology of Rhaebo nasicus (Werner, 1903) (Amphibia: Anura: Bufonidae) with the erection of a new bufonid genus and insights into the evolution of suctorial tadpoles

Abstract

Tadpoles serve as crucial evidence for testing systematic and taxonomic hypotheses. Suctorial tadpoles collected in Guyana were initially assigned to Rhaebo nasicus through molecular phylogeny. Subsequent analysis of larval and adult morphological traits revealed synapomorphies within the clade encompassing R. nasicus and R. ceratophrys, prompting the recognition of a new genus described herein as Adhaerobufo. The new genus is distinguished from other bufonids by specific phenotypic traits including an enlarged, suctorial oral disc with distinct papillae arrangements, and the presence of certain muscles and narial vacuities at the larval stage. However, only a few adult external characteristics (e.g., enlarged eyelids, infraocular cream spot), seem to be reliably discriminative from related genera. This study underscores the significance of larval morphology in anuran systematics and offers new insights into the evolution of suctorial and gastromyzophorous larvae within bufonids.