The vocal sac of Hylodidae (Amphibia, Anura): Phylogenetic and functional implications of a unique morphology

ELIAS-COSTA, AGUSTIN J.; MONTESINOS, RACHEL; GRANT, TARAN; FAIVOVICH, JULIÁN

JOURNAL OF MORPHOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2017

0362-2525

Anuran vocal sacs are elastic chambers that recycle exhaled air during vocalizations and are presentin males of most species of frogs. Most knowledge of the diversity of vocal sacs relates toexternal morphology; detailed information on internal anatomy is available for few groups of frogs.Frogs of the family Hylodidae, which is endemic to the Atlantic Forest of Brazil and adjacentArgentina and Paraguay, have three patterns of vocal sac morphology?that is, single, subgular;paired, lateral; and absent. The submandibular musculature and structure of the vocal sac mucosa(the internal wall of the vocal sac) of exemplar species of this family and relatives were studied. Incontrast to previous accounts, we found that all species of Crossodactylus and Hylodes possesspaired, lateral vocal sacs, with the internal mucosa of each sac being separate from the contralateralone. Unlike all other frogs for which data are available, the mucosa of the vocal sacs in thesegenera is not supported externally by the mm. intermandibularis and interhyoideus. Rather, the vocalsac mucosa projects through the musculature and is free in the submandibular lymphatic sac. Thepresence of paired, lateral vocal sacs, the internal separation of the sac mucosae, and their projectionthrough the m. interhyoideus are synapomorphies of the family. Furthermore, the specificconfiguration of the m. interhyoideus allows asymmetric inflation of paired vocal sacs, a featureonly reported in species of these diurnal, stream-dwelling frogs.