Physalaemus erythros Caramaschi, Feio & Guimarães, 2003

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 : 34-35

Physalaemus erythros Caramaschi, Feio & Guimarães, 2003

We found two different calls, referred to as call A and B. B calls were common in recordings in which several males were active and calling close to each other. B calls were commonly observed after overlapping periods of calls A. Call B differs from call A by its longer duration, higher fundamental frequency, presence of pulse-PAM and PFM. Additionally, the envelope of A calls is elliptic whereas that of the B calls is triangular or rectangular.

Call A ( Fig. 7 A–D and 4D). We examined 21 recordings, a total of 56 minutes, with ca. 4900 calls from 15 males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.041 to 0.077 s. The call rise and fall are similar in duration, rendering an elliptic call envelope; the call fall is gradual, whereas the call rise is steeper. The amplitude peak is at around the middle of the call duration ( Fig. 7A, C ). More than 50 % of the call energy is concentrated in 39 % of the call duration around the amplitude peak. The call has no PAM. The call is composed of harmonics ( Fig. 4D ). The harmonics are very close to each other and hardly distinguished due to the low fundamental frequency and the lack of the wave periodicity throughout the call. The fundamental frequency is approximately 250 Hz and this band can be present with low energy or absent in the audiospectrograms. The dominant frequency varies from ca. 1020 to 1160 Hz ( Fig. 7B, D ). The dominant harmonic varies from the second to the tenth, but it is usually the third. There is no clear shift in the relative energy among the bands throughout the call. Most of the call energy is between 300 and 2000 Hz (ca. seven harmonics). There is no clear general FM in the call but there are subtle irregular FM segments throughout the entire call.

Call B ( Fig. 7 E–J and 6B). We examined eight recordings, a total of 26 minutes, with 93 calls from eight males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.200 to 0.875 s. The call rise is abrupt and a little shorter than the fall, which is also very short but gradual. The call has a long sustain. The amplitude is usually regular throughout the call ( Fig. 7H ). However, in some calls, the amplitude increases gradually toward the end of the call ( Fig. 7E, G ). The amplitude peak is at the very end of the call duration ( Fig. 7E, G, H ). Depending on the slope of the sustain and the difference between the amplitude peaks, the envelope of the call can vary from rectangular ( Fig. 7H ) to triangular (pointed left; Fig. 7E, G ). More than 50 % of the call energy is concentrated in 29 % of the call duration around the amplitude peak. The call has a weak to intermediate PAM (there is no silence interval between the peaks; Fig. 7E, G, H ). The rate of the PAM is ca. 27 Hz, forming ca. 13 amplitude peaks throughout the call. The envelope of this PAM cycles is variable but the amplitude peak is at the middle of the cycle. The call is composed of harmonics ( Fig. 6B ). Usually the harmonics are clear, however, eventual decrease in the wave periodicity makes the harmonics less clear with deterministic chaos regimes. Audiospectrograms with relatively broad filter bandwidths (e.g., above 100 Hz) can show wave peaks in some parts of the call with low fundamental frequencies (minimum 107 Hz; see Table 2 ), as broadband pulses (instantaneously high sound-pressure effect; see Littlejohn 2001). The fundamental frequency is around 250 Hz and it is usually absent in the audiospectrograms. The dominant frequency varies from ca. 840 to 1780 Hz ( Fig. 7F, I, J ). The dominant harmonic varies from the third to the ninth, but it is usually the third and fourth harmonic. 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 (three to four harmonics). The frequency bands have a general upward FM throughout the call and a short downward FM at the end ( Fig. 7F, I, J ). There are irregular PFM segments throughout the entire call; these segments are usually synchronic and directly proportional to the PAM ( Fig. 7 E–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 6. Multiplicity relationship between “instantaneous” dominant frequency and w of calls B and C of six Physalaemus species. Each graph shows a single call. Call B of P. maculiventris (A), call B of P. erythros (B), call B of P. ruspestris (C), call B of P. nanus (D), call C of P. nanus (E), and call B of P. spiniger (F). 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.

FIGURE 7. Calls A and B of Physalaemus erythros. Oscillograms (A, C, E, G, and H) and audiospectrograms (B, D, F, I, and J). A single typical call A (A and B). A variant call A (C and D). A single Call B (E and F). Two calls B with variant envelopes and spectral patterns (G–J). Horizontal scale bars have 0.02 s (C–D) and 0.1 s (G–J); vertical scale bars have 1 kHz. Filter bandwidth (Hz): 92.1 (B and D); 67.4 (F, I, and J).