Hearing in the Neotropical Frog, Atelopus chiriquiensis

Few studies have measured the hearing of frequencies above 1 kHz in anurans lacking middle ear structures. Auditory frequency threshold curves were determined under similar laboratory conditions for Atelopus chiriquiensis, which lacks a tympanum, middle ear cavity, and stapes, and Hyla regilla, a similarly sized species which has these middle ear structures characteristic of most frogs. Both species were found to have similar hearing capabilities, with bimodal threshold curves and peak sensitivities at about 0.2 kHz and 2-3 kHz. This record of hearing sensitivity in a frog lacking a tympanic ear corroborates a similar observation made by Loftus-Hills in 1973 for Pseudophryne semimarmorata, which also lacks most middle ear structures and is in a different family.