Physalaemus gracilis (Boulenger, 1883)

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 : 81

Physalaemus gracilis (Boulenger, 1883)

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

Call A ( Fig. 50 A–T and 52A). We examined 40 recordings, a total of 158 minutes, with ca. 2480 calls from 106 males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.451 to 0.565 s. The envelope of the call is variable ( Fig. 50A , C–G, M–P). In most calls, rise and fall are similar in duration and shape (exponential) and the sustain is long. Some sustains are regular ( Fig. 50A, G, M, N, O ) and others are irregular, with short and shallow valleys, mainly at the beginning of the segment ( Fig. 50D, F, P ). In several calls, the sustain has a convex shape and the limits between the call rise, sustain, and call fall are not clear. Usually, the envelope is divided into two parts with different amplitude levels ( Fig. 50C ). The amplitude peak is usually at the end of the first seven tenths of the call duration. The envelope varies from elliptic or rectangular ( Fig. 50A, D, F, G, M, N, O ) to triangular (pointed left; Fig. 50C, E, P ). Due to the asymmetry of some triangular envelopes, the shape resembles an arrow. More than 50 % of the call energy is concentrated in 32 % of the call duration around the amplitude peak. There is no PAM in the call. The call has a harmonic series ( Fig. 52A ). The fundamental frequency is ca. 510 Hz and approximately the first seven harmonics are emphasized. The wave periods are regular and harmonics are clear throughout the call. Subharmonics (f 0 1/2 and f 0 1/3) are common at the beginning and middle of the call ( Fig. 50I, L, Q, R ). The dominant frequency varies from ca. 2110 to 2760 Hz ( Fig. 50B ). The dominant harmonic varies from the first to the seventh (except the second), but it is usually the fourth, fifth, or sixth ( Fig. 52A ). 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 third, fourth, fifth and sixth, and ending at the sixth or seventh; thenceforth, the dominant frequency decreases in some calls, moving to the fourth harmonic ( Fig. 52A , 50B ). Most of the call energy is between 950 and 3050 Hz (four to five harmonics). The call has a general downward FM ( Fig. 50B , H–L, Q–T). Additionally, calls have an up-downward FM in the first sixth of the call duration, leading to slightly arc-shaped bands in this part of the call, and a short downward FM at the end ( Fig. 50B , H–L, Q–T). The general downward FM and the initial up-downward FM result in S-shaped harmonics when considering the entire call. Some calls have a slight PFM ( Fig. 50H, I, L ).

Figures

FIGURE 50. Call A of Physalaemus gracilis. Oscillograms (A, C–G, and M–P) and audiospectrograms (B, H–L, and Q–T). A typical call A (A–B). Variant calls A with different envelopes and spectral features (C–T). Note the presence of subharmonics at the beginning or middle of the call (I, L, Q, and R). Horizontal scale bars have 0.5 s (C–L) and 0.2 s (M–T); vertical scale bars have 1 kHz. Filter bandwidth (Hz): 42.3 (B); 84.6 (K, L, and T); 74.6 (J); 55.2 (I and R); 69.0 (H and S); 61.4 (Q).

FIGURE 52. Multiplicity relationship between “instantaneous” dominant frequency and w of calls A of four Physalaemus species. Each graph shows a single call A of P. gracilis (A), P. lisei (B), P. evangelistai (C), P. barrioi (D), P. jordanensis (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.