Physalaemus biligonigerus (Cope, 1861)

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 : 77

Physalaemus biligonigerus (Cope, 1861)

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

Call A ( Fig. 46 A–F and 42E). We examined 29 recordings, a total of 65 minutes, with ca. 2140 calls from 105 males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.546 to 0.640 s. The envelope of the call is variable ( Fig. 46A, C, D ). In most calls, the limits between the call rise, sustain, and call fall are not clear. The ratio between call rise and fall duration, and their shapes, are highly variable. Most calls have rise and fall similar in duration, or the former longer than the fall. The shape of the envelopes varies from exponential or linear to logarithmic. The call rise can have two consecutive exponential parts, the first shorter than the second. The sustain is usually irregular, composed of shallow valleys and small peaks ( Fig. 46A, C, D ). In some calls, the call rise remains with very low amplitude until the limit with the sustain, where the amplitude increases abruptly ( Fig. 46D ). The amplitude peak is at around the end of the first third or two thirds of the call duration. The envelope varies from rectangular ( Fig. 46C ) to triangular (pointed left or right; Fig. 46D, A , respectively). Due to the asymmetry of some triangular envelopes, the shape resembles an arrow. More than 50 % of the call energy is concentrated in 30 % of the call duration around the amplitude peak. There is no PAM in the call. The call has a harmonic series ( Fig. 42E ). The fundamental frequency is ca. 570 Hz and approximately the first eight harmonics are emphasized. The wave periods are regular and harmonics are clear throughout the call. The dominant frequency varies from ca. 600 to 650 Hz ( Fig. 46B ). The dominant harmonic varies from the first to the sixth (except the second), but it is usually the first ( Fig. 42E , 46B, E, F ). There is a clear shift in relative energy between the bands; the dominant frequency gets higher toward the end of the call, starting at the first harmonic, moving to the fifth, and ending at the sixth; thenceforth it decreases, ending at the third harmonic (sometimes skipping the fourth harmonic; Fig. 42E , 46B, E, F ). Most of the call energy is between 450 and 2950 Hz (four to six harmonics). The call has a general downward FM ( Fig. 46B, E, F ). Additionally, the calls have an up-downward FM in the first fifth of the call duration, leading to a arc-shaped bands in this part of the call, and a short downward FM at the end ( Fig. 46B, 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 42. Multiplicity relationship between “instantaneous” dominant frequency and w of calls A of eight Physalaemus species. Each graph shows a single call A of P. orophilus (A), P. lateristriga (B), P. olfersii (C), P. riograndensis (D), P. biligonigerus (E), P. marmoratus (F), P. santafecinus (G), P. carrizorum (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. Factors multiple of ½ of the fundamental frequency correspond to subharmonics (see call B of P. ephippifer).

FIGURE 46. Call A of Physalaemus biligonigerus. Oscillograms (A, C, and D) and audiospectrograms (B, E, and F). A typical call (A–B). Variant calls with different envelopes and spectral features (C–F). Note the shorter duration of the initial FM segment (F). Horizontal scale bars have 0.1 s; vertical scale bars have 1 kHz. Filter bandwidth (Hz): 61.9 (B); 62.8 (E); 69.0 (F). Pulses of high frequency in the background in (F) correspond to calls of Pseudopaludicola sp.