Physalaemus albifrons (Spix, 1824)

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 : 60

Physalaemus albifrons (Spix, 1824)

We found a single call type for the species, referred to as call A. The call is composed of a short single harmonic note with an elliptic envelope. It has a general downward FM throughout the call but with an up-downward FM segment in the first three fourths of the call duration.

Call A ( Fig. 28 A–F and 24E). We examined two recordings, a total of two minutes, with ca. 90 calls from two males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.263 to 0.297 s. The call rise and fall durations are similar to each other in duration and shape (linear to exponential). There is a sustain, usually with a concave shape, yielding two amplitude peaks around the middle of the call ( Fig. 28A ). The amplitude peak is at around the middle of the call duration. The envelope is elliptic ( Fig. 28A, C ). More than 50 % of the call energy is concentrated in 24 % of the call duration around the amplitude peak. There is no PAM in the call. The call has a harmonic series ( Fig. 24E ). The fundamental frequency is ca. 480 Hz and approximately the first seven harmonics are emphasized. The wave periods are regular and harmonics are clear throughout the call. The dominant frequency varies from ca. 2440 to 2670 Hz ( Fig. 28B ). The dominant harmonic varies from the second to the ninth, but it is usually the fifth. There is a clear shift in the relative energy among the bands; the dominant frequency gets higher toward the end of the call, starting at the second harmonic and ending at the eighth or ninth ( Fig. 28B, E, F ; 24E ). Thenceforth, it gets lower, ending in the seventh or sixth harmonic ( Fig. 28B, E, F ; 24E ). Most of the call energy is between 1100 and 3700 Hz (six to nine harmonics). The call has a general downward FM ( Fig. 28B, E, F ). Additionally, the calls have an up-downward FM in the first three fourths of the call duration, yielding arc-shaped bands in this part of the call and a short downward FM at the end ( Fig. 28B, E, F ). The general downward FM and the initial up-downward FM result in S-shaped harmonics when considering the entire call. There is no PFM.

Figures

FIGURE 24. Multiplicity relationship between “instantaneous” dominant frequency and w of calls A of eight Physalaemus species. Each graph shows a single call A of P. henselii (A), P. albonotatus (B), P. cuqui (C), P. atim (D), P. albifrons (E), P. erikae (F), P. kroyeri (G), P. centralis (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 of the measured acoustic oscillation. Note that factors around integer values suggest harmonic relationship between the frequency calculated (w reciprocal) and the dominant frequency. The heterogeneity of the factors in P. henselii (A) suggests sidebands.

FIGURE 28. Call A of Physalaemus albifrons. Oscillograms (A, C, and D) and audiospectrograms (B, E, and F). A single typical call with elliptic envelope (A–B). Variant calls with different envelopes and levels of FM (C–F). Horizontal scale bars have 0.1 s; vertical scale bars have 1 kHz. Filter bandwidth (Hz): 92.1 (B); 81.2 (E); 78.9 (F).