SPHENOPHRYNE - American Museum of Natural History

2000 ZWEIFEL: PARTITION OF SPHENOPHRYNE
115
Fig. 73. Outline drawings of sacral regions of Austrochaperina and Sphenophryne in dorsal view;
scale bars marked in millimeters. A. A. rivularis, AMNH A88445. B. A. basipalmata, AMNH A129495.
C. A. palmipes, AMNH A92805. D. A. derongo, AMNH A92794. E. A. blumi, UPNG 9959. F. S.
cornuta, AMNH A92803.
modulation within a note. A call is a unit of
vocalization that may consist of a single note
(when the period between notes is long with
respect to the note duration and often is irregular)
or may comprise notes rapidly repeated.
Multinote calls may occur as short
bursts of sound or may continue for long periods,
sometimes seemingly indefinitely.
Subjectivity in classifying notes and pulses
Fig. 74. Right lateral view of jaw musculature
of Oxydactyla stenodactyla. Scale bar marked in
millimeters.
occurs when the amplitude variation of pulses
(as seen in an expanded waveform) approaches
or attains 100% but with little quiet
space intervening. For descriptive purposes,
it generally is best to let the ear dictate the
classification in such cases.
A conspicuous dichotomy in the calls lies
between those in which the notes are pure,
unpulsed tones, and those whose notes are
pulsed, giving a harsher sound sometimes
characterized as a chirp. Calls with notes (or
pulses) too rapidly repeated to be resolved
by the human ear are heard as a buzz; none
of the species discussed here has this type of
call. The other major variable involves the
organization of notes into calls. I identify
three levels of increasing complexity: (1)
calls consisting of a single note, which is repeated
at intervals wide with respect to the
duration of the note and is generally irregular;
(2) calls including a train of similar notes
repeated relatively rapidly and extending
over long periods; (3) calls in which rather
standardized groups of notes are uttered as
units separated by silent periods of variable