Living in fast-water: morphology of the gastromyzophorous tadpole of the bufonid Rhinella quechua (R. veraguensis group).

Abstract

We describe the bufonid gastromyzophorous tadpoles of Rhinella quechua from montane forest streams in Bolivia. Specimens were cleared and stained, and the external morphology, buccopharyngeal structures, and the musculoskeletal system were studied. These tadpoles show a combination of some traits common in Rhinella larvae (e.g., emarginate oral disc with large ventral gap in the marginal papillae, labial tooth row formula 2/3, prenarial ridge, two infralabial papillae, quadratoorbital commissure present, larval otic process absent, mm. mandibulolabialis superior, interhyoideus posterior, and diaphragmatopraecordialis absent, m. subarcualis rectus I composed of three slips), some traits apparently exclusive for the described species of the R. veraguensis group (e.g., second anterior labial tooth row complete, lingual papillae absent, adrostral cartilages present), and some traits that are shared with other gastromyzophorous tadpoles (e.g., enlarged oral disc, short and wide articular process of the palatoquadrate, several muscles inserting on the abdominal sucker). In the context of the substantial taxonomic and nomenclatural changes that the former genus Bufo has undergone, and despite the conspicuous morphological differences related to the presence of an abdominal sucker, the larval morphology of R. quechua supports including it in the genus Rhinella and placing it close to species of the R. veraguensis assemblage.