LARSON, P.M.*; DE S�, R.O.; ARRIETA, D.; Ohio University; University of Richmond; Montevideo, Uruguay: Chondrocranial, hyobranchial, and internal oral morphology in the basal bufonid genus Melanophryniscus (Amphibia: Anura)

Melanophryniscus is a genus of small toads inhabiting the southern portion of South America. This genus is considered basal within the family Bufonidae. Data on larval chondrocranial morphology do not exist for the genus and larval internal oral anatomy has only been described for a single species. Herein, we describe chondrocranial and internal oral morphology in Melanophryniscus montevidensis, M. orejasmirandai, and M. sanmartini. Chondrocranial morphology is similar among species examined. Comparisons with other bufonids and with outgroup taxa suggest that the following chondrocranial characters may represent synapomorphies for the Bufonidae: poorly developed orbital cartilages, free (or absent) ceratobranchial IV, a reduced or absent larval crista parotica, and the lack of a larval otic process. The presence of an elongated processus anterior dorsalis of the suprarostral alae and the absence a chondrified commissura quadratoorbitalis appear to be unique in Melanophryniscus among bufonids. Internal oral anatomy is conserved in Melanophryniscus and among bufonids in general.