Dendropsophus cruzi ( Pombal & Bastos, 1998 )

Andreani, Tainã Lucas, Oliveira, Seixas Rezende, Guerra, Vinícius, Bastos, Rogério Pereira & Morais, Alessandro Ribeiro De, 2018, The aggressive call of Dendropsophus cruzi (Pombal & Bastos, 1998) (Anura; Hylidae) in Central Brazil, Zootaxa 4379 (1), pp. 137-139 : 137-138

Dendropsophus cruzi ( Pombal & Bastos, 1998)

is a small hylid (male snout-to-vent length = 16.3–19.4 mm; female SVL = 21.3–25.0 mm) that is allocated in the D. microcephalus group ( Faivovich et al. 2005). It is commonly found in Open and forested areas from Central Brazil to Provincia Velasco, Departamento de Santa Cruz, Bolivia ( Frost 2017; Tessarolo et al. 2016). Pombal & Bastos (1998) described the advertisement call of D. cruzi as a single pulsed note. Posteriorly, studies uncovered relationships between dominant frequency variation in the advertisement calls of D. cruzi and variation in the SVL and mass of males ( Bastos et al. 2003), as well as the existence of a clinal geographic pattern in the variation of acoustic parameters of these calls ( Tessarolo et al. 2016). However, the acoustic communication in anurans is usually mediated by more than one vocalization type ( Toledo et al. 2015). Due the importance of call types in the social context of anurans (e.g., Reichert 2011; Forti et al. 2017), we expand the vocal repertoire of D. cruzi by describing its aggressive call.

We recorded the advertisement and aggressive calls of nine males of D. cruzi at different ponds located in municipalities of Itajá (18°53’44” S, 51°40’24” W; 511 m a.s.l.; n = 5 males; November 2016), Caldas Novas (17°49'41" S, 48°39'05" W; 805 m a.s.l.; n = 1 male; November 2014), Pilar de Goiás (14°48’31.61” S, 49°31’36.36” W; 736 m a.s.l.; n = 1 male; February 2017), and Rio Verde (17°50’46.84” S, 50°52’23.41” W; 672 m a.s.l.; n = 2 males; December 2016), State of Goiás, Central Brazil. In all cases, we observed males during acoustic interactions with conspecific individuals (territorial dispute; Toledo et al. 2015), and two of these interactions escalated to physical combat. We obtained the vocalizations using a Marantz PMD 660 or TASCAN DR-40 recorder (sample rate 44 kHz and 16-bit resolution, stored in.wav files) with a Sennheiser ME66 microphone placed at about 50 cm from the calling frog. All recordings were conducted during the night (from 19:00h to 00:00h). Voucher specimens were deposited at the Zoological Collection of Universidade Federal de Goiás (ZUFG 9577) and at the Herpetological Collection of Instituto Federal Goiano, Campus Rio Verde (IFRV 390-95).

For each recorded individual, we analyzed five advertisement calls and all emitted aggressive calls. We used Raven Pro 1.4 ( Bioacoustics Research Program 2011) to analyze the temporal and spectral parameters of the calls. The following parameters were measured: pulse rate (pulses/s), call duration (s), pulse number (pulses/calls), pulse duration (s), dominant frequency (Hz), upper and lower frequencies (Hz), frequency amplitude (Hz), and total repetition rate (calls/min) (see Forti et al. 2015). Call description and terminology followed Toledo et al. (2015). Spectrograms and waveforms were prepared using the R package Seewave 1.6.4 ( Sueur et al. 2008), with the following settings: window name (Fourier transform window) = Hanning; window length = 256 samples; overlap = 90%.

The advertisement call ( Fig. 1 ) of D. cruzi was composed by a single pulsed note and the call duration varied from 0.006 to 0.023 s (mean = 0.013 ± 0.004 s; n = 50 calls). The pulse number and pulse duration varied, respectively, from 1 to 8 pulses/call (X = 3.775 ± 1.49; n = 50 calls) and from 0.002 to 0.008 s (mean = 0.003 ± 0.001 s; n = 150 pulses). Pulse rate ranged from 166.66 to 347.82 pulses/s (mean = 278.21 ± 42.59 pulses/s; n = 50 calls). Repetition rate ranged from 88 to 238 calls/minute (mean = 167.12 ± 50.17 calls/minute; n = 9 males). Dominant frequency ranged from 4478.9 to 7312.5 Hz (mean = 6476.74 ± 688.4 Hz; n = 50 calls), upper frequency from 4823.4 to 7687.5 Hz (mean = 6834.64 ± 719.03 Hz; n = 50 calls), lower frequency from 4134.4 to 6937.5 Hz (mean = 6106.69 ± 702.72 Hz; n = 50 calls), and frequency amplitude from 689 to 750 Hz (mean = 727.94 ± 113.22 Hz; n = 50 calls).

Aggressive calls were also composed by a single pulsed note ( Fig. 1 ). Call duration varied from 0.033 to 0.45 s (X = 0.159 ± 0.087 s; N = 65 calls), while pulse rate varied from 162.22 to 292.37 pulses/s (X = 228.82 ± 27.27 pulses/s; N = 65 calls). The pulse number and pulse duration varied, respectively, from 8 to 73 pulses/call (X = 35.7 ± 17.98; N = 65 calls) and from 0.0008 to 0.003 s (X = 0.002 ± 0.0006s; N = 195 pulses). Dominant frequency varied from 4995.7 to 7125 Hz (X = 6214.29 ± 473.81 Hz; N = 65 calls), upper frequency varied from 5168 to 8062.5 Hz (X = 7588.28 ± 1886.51 Hz; N = 65 calls), lower frequency varied from 4306.6 to 6187.5 Hz (X = 5423.17 ± 641.76 Hz; N = 50 calls), and frequency amplitude varied from 750 to 3375 Hz (X = 1598.53 ± 787.58 Hz; N = 65 calls).

The advertisement call of D. cruzi agree in terms of call properties with all previous descriptions ( Pombal & Bastos 1998; Bastos et al. 2003; Tessarolo et al. 2016). Call duration, pulse number, pulse duration, upper frequency and frequency amplitude were higher in aggressive calls than in advertisement calls, whereas pulse duration and lower frequency were higher in advertisement calls. Aggressive calls were only emitted by males in the presence of a nearby conspecific male, in a context of defence of the calling site.

The Dendropsophus microcephalus group contains more than 30 species ( Faivovich et al. 2005; Frost 2017) of which few have their aggressive calls described (e.g., D. ebraccatus , D. phlebodes and D. microcephalus— Schwartz & Wells 1985; D. werneri — Lingnau et al. 2004). The aggressive call of D. cruzi has a higher pulse number than those of D. werneri ( Lingnau et al. 2004) and higher dominant frequency than D. werneri , D. microcephalus , D. ebraccatus and D. phlebodes ( Schwartz & Wells 1985; Lingnau et al. 2004). Despite extensive research on anuran bioacoustics ( Toledo et al. 2015), little is known about aggressive calls, and our results contribute to improve the knowledge about the bioacustics of the D. microcephalus group.

Figures

FIGURE 1.Spectrogram (top) andoscilogram(bottom) ofthe advertisement andaggressive calls) of Dendropsophus cruzifromItajá municipality,state of Goiás, Brazil (air temperature = 22.6°C; SVL = 17.5; mass = 0.2 g).