Physalaemus obtectus Bokermann, 1966

Hepp, Fábio & Pombal, José P., 2020, Review of bioacoustical traits in the genus Physalaemus Fitzinger, 1826 (Anura: Leptodactylidae: Leiuperinae), Zootaxa 4725 (1), pp. 1-106 : 38

Physalaemus obtectus Bokermann, 1966

We found a single call type for the species, referred to as call A. The call is composed of a sequence of pulses. There are clear harmonics, however deterministic-chaos regimes can be present at the beginning of the pulses where jumps of the fundamental frequency are common.

Call A ( Fig. 10 A–J and 4G). We examined seven recordings, a total of eight minutes, with ca. 280 calls from eight males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.415 to 0.553 s. Usually, call rise and fall durations are similar, both resembling logarithmic shape; the amplitude peak is at around (usually just before) the middle of the call duration ( Fig. 10A, D, E, F ). However, some calls have an exponential or linear rise, followed by a long sustain and an abrupt fall ( Fig. 10C ). In calls with rise and fall similar in slope and duration, the envelope of the call is symmetric ( Fig. 10A, D, E, F ), whereas in calls with sustain the envelope is rectangular or triangular (pointed left; Fig. 10C ). More than 50 % of the call energy is concentrated in 35 % of the call duration around the amplitude peak. The call has pulse-PAM (with silence intervals present between pulses; Fig. 10 A–J). The rate of the PAM is ca. 9 Hz, forming ca. four pulses throughout the call. The pulses of the first half of the call have rise similar to fall and the amplitude peak is at the middle of the pulse. On the other hand, the pulses of the second half have rises sharper and shorter than falls, which are more gradual, with amplitude peaks at the beginning of the pulses ( Fig. 10A, D, E, F ). In some calls, the last pulse is clearly shorter than the others ( Fig. 10E ). There is a long silence interval between the pulses, equivalent to ca. 1.5 times the pulse duration. The call has a harmonic series ( Fig. 4G ). The fundamental frequency is ca. 380 Hz and this band can be present with low energy or absent in the audiospectrograms. Most of the wave periods are regular and the harmonics are clear throughout the call. However, subharmoncis, deterministic chaos, and jumps of the fundamental frequency are observed at the beginning and end of the pulses ( Fig. 10H, I ). At the same parts of the pulse, the low fundamental frequency can lead to the wave peaks to be shown as broadband clicks (instantaneously high sound-pressure effect; see Littlejohn 2001) in audiospectrograms at broad filter bandwidths. The dominant frequency varies from ca. 1210 to 1230 Hz ( Fig. 10B ). The dominant harmonic varies from the third to the seventh, but it is usually the third or fourth. There is no clear shift in the relative energy among the bands throughout the call. Most of the call energy is between 800 and 1600 Hz (often, two or three harmonics). The frequency bands have a general upward FM throughout the call ( Fig. 10B, G, I, J ). Additionally, there is PFM throughout the call, which is directly proportional to the synchronic pulse-PAM, i.e., each pulse has an up-downward FM ( Fig. 10A, B , D–F, H–J).

Figures

FIGURE 4. Multiplicity relationship between “instantaneous” dominant frequency and w of calls A of seven Physalaemus species. Each graph shows a single call A of: P. nattereri (A), P. maculiventris (B), P. erythros (C), P. rupestris (D), P. camacan (E; F), P. obtectus (G), P. irroratus (H). Grid corresponds to the harmonic values (right y-axis). Red squares are the values of “instantaneous” dominant frequency; blue circles are the values of the reciprocal of w; green triangles are the factor values of the ratio “instantaneous” dominant frequency / w reciprocal per delta time. Delta time corresponds to the duration of one period w of the measured oscillation. Note that factors around integer values suggest harmonic relationship between the frequency calculated (w reciprocal) and the dominant frequency. Factors multiple of ½ of the fundamental frequency correspond to subharmonics (see P. irroratus; H).

FIGURE 10. Call A of Physalaemus obtectus. Oscillograms (A, C, D, E, and F) and audiospectrograms (B, G, H, I, and J). A single typical call (A and B). Variant calls with different envelopes, number of pulses, pulse durations, and interpulse intervals (C–J). Horizontal scale bars have 0.1 s; vertical scale bars have 1 kHz. Filter bandwidth (Hz): 67.4 (G, I, and J); 78.9 (H); 61.9 (B).