Hyperextended call note repertoire of the endemic Madagascar treefrog Boophis madagascariensis (Rhacophoridae)

Vocalizations of Boophis madagascariensis (Rhacophoridae) males were record ed in a mid-elevation rain forest in eastern Madagascar. Call notes made by males of this species were classified into 28 types. This represents the l argest known call repertoire of any amphibian. The calls range widely in sp ectral characteristics from a narrowband, nearly pure-tone to broadband 'ri p' notes, to even broader band, pulsatile 'iambic' notes consisting of up t o 23 pulses. Even considering all 'iambic' notes as variants of one type, t here remain eight distinct call notes produced by this species. Morphologic al analysis of the vocal musculature of B. madagascariensis revealed no obv ious adaptations for unusual glottal flexibility or function. Playback stud ies using a subset of the call notes as stimuli were carried out in the ani mals' natural habitat to determine the functional significance of several o f the call notes. At the lowest playback levels, there was a significant te ndency for males to produce rip notes in immediate response to either rip o r iambic note stimuli. At the higher playback levels, we identified one seq uence of iambic notes that consistently evoked a significant iambic note re sponse from males. A permutation test on call note transitions during spont aneous calling revealed that call note pairs occurred inconsistently and un predictably. The evolutionary significance of an extended vocal repertoire, matched counter-calling and a random call note production scheme is discus sed.