Physalaemus spiniger (Miranda-Ribeiro, 1926)

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 : 43

Physalaemus spiniger (Miranda-Ribeiro, 1926)

We found two different calls, referred to as call A and B. Calls A and B are composed of harmonics and a single note each. Call B has two very different components. The first component is similar to call A, whereas the second one is composed of nonlinear regimes such as deterministic chaos and subharmonics.

Call A ( Fig. 14 A–L and 13B). We examined 16 recordings, a total of 43 minutes, with ca. 800 calls from 12 males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.221 to 0.492 s. The envelope of the call is highly variable ( Fig. 14A , C–G). Often, the call rise and fall are similar in duration and vary from linear to exponential shape; there is a long regular sustain or a shallow valley connecting them ( Fig. 14A, C ). The amplitude peak of the calls is at around the end of the first three fourths of the call duration. The envelope of the call can be elliptic ( Fig. 14D, F ), rectangular ( Fig. 14A, C ), or triangular ( Fig. 14E, G ) depending on the shape of the sustain. There can be a short and deep amplitude valley at the beginning of the call ( Fig. 14G ). More than 50 % of the call energy is concentrated in 35 % of the call duration around the amplitude peak. The call has no PAM. The call has a harmonic series ( Fig. 13B ). The fundamental frequency is ca. 380 Hz and this band can be present with low energy or absent in the audiospectrograms. The wave periods are regular and the harmonics are clear throughout the call. The dominant frequency of the call varies from 1120 to 1981 Hz ( Fig. 14B ). The dominant harmonic varies from the second to the sixth, but it is usually the fourth. There is no clear shift in the relative energy between the bands throughout the call. Most of the call energy is between 1100 and 1700 Hz (ca. two or three harmonics). The call usually has a general upward FM ( Fig. 14I, J, K ), a few calls have downward FM ( Fig. 14B, H, L ). Additionally, many calls have a rapid up-downward FM at their outset, forming arc-shaped bands in this part of the call and a short downward FM at the end ( Fig. 14B, J, K, L ). In calls with short amplitude valleys the bands have down-upward FM, synchronically to the valley ( Fig. 14L ). Some calls showed a slight PFM ( Fig. 14I, J ).

Call B ( Fig. 14 M–P and 6F). We examined two recordings, a total of five minutes, with seven calls from three males. Most of these calls were measured (see Table 2 ). Call duration varies from 0.376 to 0.512 s. The call rise and fall are short and similar in duration; there is a long irregular sustain ( Fig. 14M, O ). The amplitude peak is at around the middle of the call duration. Shallow amplitude valleys are present yielding secondary amplitude peaks at the beginning and end of the call. The envelope of the call is somewhat rectangular ( Fig. 14M, O ). More than 50 % of the call energy is concentrated in 43 % of the call duration around the amplitude peak. The call has no PAM. The call has a harmonic series ( Fig. 6F ). The call has two different components. The traits of the first component are similar to those of the call A, whereas in the second component, the harmonics can be not well defined due to deterministic chaos (high irregularity of the wave periods; Fig. 14N, P ). Subharmonics are common in the second component of the call ( Fig. 14N, P ). The fundamental frequency is ca. 290 Hz. Although the amplitude often decreases slightly at the transition between components, their limits can be unclear in oscillograms ( Fig. 14M ). The dominant frequency of the call varies from 1163 to 1723 Hz ( Fig. 14N ). The dominant harmonic of the second component varies from the third to the 12 th, but it is usually the fourth, fifth, or sixth. There is a slight increase in the relative energy of the higher harmonics throughout the call ( Fig. 14N, P ). Most of the second component’s energy is between 1200 and 2000 Hz (ca. three harmonics). The general FM is usually downward, with no additional FM at the end ( Fig. 14N, P ). Some calls have an up-downward FM at the beginning, yielding arc-shaped bands in this part of the call ( Fig. 14N ). In highly variable calls, and mainly along the second component, there can be several parts with irregular up and downward FM mirroring the AM direction ( Fig. 14N, P ).

Figures

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 13. Multiplicity relationship between “instantaneous” dominant frequency and w of calls A of eight Physalaemus species. Each graph shows a single call A of: P. nanus (A), P. spiniger (B), P. crombiei (C), P. signifer (D), P. bokermanni (E), P. angrensis (F), P. atlanticus (G), P. moreirae (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 P. nanus; A).

FIGURE 14. Calls A and B of Physalaemus spiniger. Oscillograms (A, C–G, M, and O) and audiospectrograms (B, H–L, N, and P). A single typical call A (A and B). Variant calls A with different envelopes and spectral features (C–L). Calls B (M–P). Horizontal scale bars have 0.1 s; vertical scale bars have 1 kHz. Filter bandwidth (Hz): 50.7 (N and P); 61.9 (B); 110.0 (H); 97.6 (I); 74.6 (J and K); 84.6 (L).