Physalaemus riograndensis Milstead, 1960

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 : 76

Physalaemus riograndensis Milstead, 1960

We found a single call type for the species, referred to as call A. The call is composed of a single harmonic note with high fundamental frequency (ca. 1000 Hz). It has a general downward FM throughout the call, with an up-downward FM segment in the its first third.

Call A ( Fig. 45 A–F and 42D). We examined 14 recordings, a total of 31 minutes, with ca. 820 calls from 50 males. Only some of these calls were measured (see Table 2 ). Call duration varies from 0.691 to 0.835 s. The envelope of the call is variable ( Fig. 45A, C, D ). In most calls, the limits between the call rise, sustain, and call fall are not clear. Calls usually have a short segment with very low amplitude at the beginning of the call, separated from the rest of the call by an abrupt change in amplitude. The shape of the call rise and fall is usually exponential. The sustain is irregular, usually composed of a shallow or deep valley (i.e., with a concave shape; Fig. 45D ). The amplitude peak is often at around the middle or after one third of the call duration. The envelope varies from elliptic ( Fig. 45A, D ) to triangular (pointed right; Fig. 45C ). Due to the concave shape of the sustain, the triangular shape of some calls resembles an arrow. More than 50 % of the call energy is concentrated in 27 % of the call duration around the amplitude peak. There is no PAM in the call. The call has a harmonic series ( Fig. 42D ). The fundamental frequency is ca. 1020 Hz and the first six harmonics are generally emphasized. The wave periods are regular and harmonics are clear throughout the call. The dominant frequency varies from ca. 950 to 1030 Hz ( Fig. 42D ). The first harmonic is the dominant ( Fig. 42D , 45B, E, F ). There is a clear shift in relative energy among bands. Although, usually, there is no shift in the dominant frequency, the higher bands get more energy towards the end of the call ( Fig. 42D ). Most of the call energy is between 850 and 1150 Hz (one harmonic). The call has a general downward FM (45B, E, F). Additionally, calls have an up-downward FM in the first third of the call duration, leading to arc-shaped bands in this part of the call, and a short upward FM at the end (45B, E, F). The general downward FM and the initial updownward 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 45. Call A of Physalaemus riograndensis. Oscillograms (A, C, and D) and audiospectrograms (B, E, and F). A typical call (A–B). Variant calls with different envelopes (C–F). Horizontal scale bars have 0.2 s; vertical scale bars have 1 kHz. Filter bandwidth (Hz): 92.1 (E and F); 42.3 (B).