Physalaemus signifer (Girard, 1853)

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 : 47

Physalaemus signifer (Girard, 1853)

We found two different calls, referred to as call A and B. Calls B were recorded in agonistic contexts (M. Bilate, personal communication). Calls A and B are composed of harmonics and a single note each. Call B tends to be longer and with lower fundamental frequency than Call A. Calls B have strong FM segments and nonlinear regimes, such as deterministic chaos and subharmonics.

Call A ( Fig. 17 A–L and 13D). We examined 68 recordings, a total of 213 minutes, with ca. 5800 calls from 135 males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.453 to 0.579 s. Call rise and fall are short and usually similar to each other in duration. In some calls, the rise is longer than the fall ( Fig. 17A, C, D, F ). Both can have a linear or exponential shape. There is a long sustain ( Fig. 17A, C, D, E, F, G ). Usually it has a convex shape it can be quite irregular with periods of concave (amplitude valley) and convex shapes ( Fig. 17E, D , respectively). In some calls the rise and the sustain can be fused. The amplitude peak of the call is at around the end of the first four fifths of the call duration ( Fig. 17A, C, E, F ). The envelope of the call can be classified as elliptic ( Fig. 17D ), rectangular ( Fig. 17F, G ), or triangular (pointed left; Fig. 17A, C, E ) depending on the shape of the sustain and position of the amplitude peak in the call. More than 50 % of the call energy is concentrated in 34 % of the call duration around the amplitude peak. Some calls have a slight PAM (there is no silence interval between the amplitude peaks; Fig. 17 C, E, G ). The rate of the PAM is ca. 50 Hz, forming ca. 22 cycles throughout the call. The cycle rise and fall are similar, with amplitude peak at the middle of the cycle. The call has a harmonic series ( Fig. 13D ). The fundamental frequency is ca. 280 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. Subharmonics are present at the very end of some calls. The dominant frequency varies from ca. 860 to 1550 Hz ( Fig. 17B ). The dominant harmonic varies from the third to the fifth harmonic, but it is usually the third. There is no clear shift in the relative energy between the bands throughout the call. Most of the call energy is between 700 and 1000 Hz (two harmonics). Usually, the call has a general upward FM with a short downward FM at the end ( Fig. 17B, H, I, J, K, L ). Some calls have an up-downward FM at the beginning, yielding arc-shaped bands in this part of the call ( Fig. 17L ). Additionally, there is PFM throughout the call, which is directly proportional to the synchronic PAM ( Fig. 17C, E, G, H, J, L ).

Call B ( Fig. 17 M–R and 16B). We examined two recordings, a total of eight minutes, with 64 calls from four males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.883 to 1.355 s. Call rise and fall are short and usually similar in duration. In some calls, the rise is longer than the fall. Both can have a linear or exponential shape. There is a long sustain, usually very irregular, with several amplitude peaks ( Fig. 17M, O, P ). The highest amplitude peak is at around the end of the first nine tenths of the call duration (see below; Fig. 17M, O, P ). The envelope of the call can be classified as elliptic, rectangular, or triangular (pointed left; Fig. 17M, O, P ) depending on the shape of the sustain and position of the amplitude peak in the call. More than 50 % of the call energy is concentrated in 40 % of the call duration around the amplitude peak. The call has an irregular PAM (there is no silence interval between the amplitude peaks; Fig. 17M ). Amplitude peaks are variable in intensity and some of them can show high amplitude. Usually, that is the case of the last peak, where the amplitude peak of the call is. The rate of the PAM is ca. 19 Hz even though highly variable, forming ca. 14 peaks throughout the call. The cycle ride and fall are usually similar, with amplitude peak at the middle of the cycle. The call has a harmonic series ( Fig. 16B ). The fundamental frequency is ca. 230 Hz and this band can be present with low energy or absent in the audiospectrograms. Usually the wave periods are regular and harmonics are clear throughout the call. However, some parts of the call can have poorly distinguished harmonics, with considerably deterministic chaos due to the high irregularity of the wave periods ( Fig. 17Q ). Sudden jumps of the fundamental frequency can be present (usually at the end of the call; Fig. 17Q ). Moreover, some calls show subharmonics, usually at their ends ( Fig. 17N ). The dominant frequency varies from ca. 840 to 950 Hz ( Fig. 17N ). The dominant harmonic varies from the third to the fifth harmonic, 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 600 and 1200 Hz (two or three harmonics). The call has a general upward FM with a short downward FM at the end ( Fig. 17N, Q, R ). Additionally, there is a remarkable PFM throughout the call, which is directly proportional to the synchronic PAM where the latter is present ( Fig. 17 M–R).

Figures

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 16. Multiplicity relationship between “instantaneous” dominant frequency and w of calls B of five Physalaemus species. Each graph shows a single call B of: P. crombiei (A), P. signifer (B), P. bokermanni (C), P. angrensis (D), and P. moreirae (E). 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 17. Calls A and B of Physalaemus signifer. Oscillograms (A, C–G, M, and O–P) and audiospectrograms (B, H–L, N, and Q–R).A single typical call A (A and B). Variant A calls with different envelopes and level of periodic amplitude modulation (C–L). Calls B (M–R). Horizontal scale bars have 0.1 s; vertical scale bars have 1 kHz. Filter bandwidth (Hz): 48.8 (I–H, N, and R); 50.7 (J); 69.0 (B); 55.2 (K); 42.3 (L and Q).