Silent sounds in the Andes: Underwater vocalizations of three frog species with reduced tympanic middle ears

BRUNETTI, ANDRÉS E; MUÑOZ, ARTURO S.; BARRIONUEVO, J. SEBASTIÁN; REICHLE, STEFFEN

CANADIAN JOURNAL OF ZOOLOGY

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Lugar: Otawa; Año: 2017

0008-4301

Underwater vocalization in anurans is restricted to a few, distantly related species. In some of them, sound is transmitted through tympanic and extratympanic pathways. Members of the Andean genus Telmatobius (Wiegmann 1834) lack a tympanic membrane, and earlier reports assumed the absence of vocalizations in the genus. We recorded underwater vocalizations and examined the middle-ear morphology in three species of Telmatobius with different lifestyles: T. oxycephalus (Vellard 1946), semiaquatic, riverine; T. hintoni (Parker 1940), markedly aquatic, riverine; and T. culeus (Garman 1876), fully aquatic, lacustrine. Males emit underwater calls, which in the three species are simple and stereotyped; they consist of a repeated train of notes, with a low fundamental frequency (309−941 Hz). In each of the three species, the tympanic membrane is absent and the tympanic cavity is reduced (T. oxycephalus) or almost nonexistent (T. hintoni and T. culeus), whereas the opercular system is well developed. Our data, along with prior knowledge in other species of anurans, suggest that the species examined here probably perceived sound through extratympanic pathways. Given the limited knowledge about underwater calling in anurans, Telmatobius seems a logical candidate to study the functional and evolutionary bases of underwater hearing and tympanic middle-ear reduction in anurans.