Vocal sacs in Hylodidae (Amphibia, Anura)

AGUSTIN JORGE ELIAS COSTA; RACHEL MONTESINOS; TARAN GRANT; JULIÁN FAIVOVICH

Hangzhou, Zhejiang, China

Congreso; 8th World Congress of Herpetology; 2016

Chinese Herpetological Society

Adult males of most anurans have vocal sacs ? expandable chambers used to cycle air between the oral cavity and lungs during vocalization. Vocal sacs are evaginations of the buccal floor supported ventrally by the Mm. intermandibularis and interhyoideus. In most species, the vocal sac is simple and subgular; however, some species possess paired, lateral sacs, whereas others lack vocal sacs altogether. Unfortunately, most knowledge of vocal sac diversity is based only on external morphology. The term ?paired sacs? itself (commonly used in taxonomic literature) makes no reference to how those sacs are organized internally, so there is a great amount of variation that remains unstudied. The Atlantic Forest endemic family Hylodidae has been reported to possess the three patterns of vocal sacs (single, paired, and absent), making it an excellent model to study this variation. Thus, we examined the submandibular musculature and vocal sac structure of representative species of this family and close relatives. We found that the anatomy of the paired vocal sacs of hylodids is unique among the multiple independent origins of paired vocal sacs in Anura. Further, the specific arrangement of muscles suggests a mechanism to allow asymmetric inflation of the vocal sac, which has implications for visual communication in these frogs.