Bioacoustics of Sphaenorhynchus surdus

Description of Holotype . Provided by Cochran (1953) . Advertisement call. Adult males of S. surdus call from the floating vegetation, generally in the deepest portion of temporary or permanent ponds ( Figure 2 ). The advertisement call was described in words by Cochran (1953) as “hitting resonant rocks together quickly 4 or 5 times”. The advertisement call of S. surdus , recorded all over its distribution (municipalities of São Bento do Sul, Lebon Régis, Ponte Serrada, Urubici, Lages, and Lontras, all in the state of Santa Catarina, and municipality of São José dos Ausentes, state of Rio Grande do Sul), but in the type locality, has from 18 to 22 notes, ranging from 1.34 ± 0.13 kHz (range: 0.98 – 1.54; n = 27 notes; 1 male ) to 3.41 ± 0.17 kHz (range: 3.17 – 3.85; n = 27 notes; 1 male ). The mean dominant frequency is 2.29 ± 0.03 kHz (range: 2.24 – 2.37; n = 27 notes; 1 male ). The duration of the call is about 1.7 seconds, but it depends on the number of notes in the calls. The mean duration of an individual note is 0.02 ± 0.004 s (0.01 – 0.03; n = 27 notes; 1 male ). The first two notes differ from the remaining by having a much more pulsed structure. There is a short interval between the notes (mean: 0.07 ± 0.007 s ; range: 0.05 – 0.08; n = 27 notes; 1 male ) ( Table 1 ; Figure 3 ). Species / Locality Duration of Frequency (kHz) Notes / call Duration of Interval Notes type (N) the call (s) or Pulses / the note (ms) between notes note (ms) Minimum Maximum Dominant S. surdus / notes type I (1 male / 4 calls / 27 notes) Lebon Régis, SC 1.55–1.99 1.34±0.13 (0.98–1.54) 3.41±0.17 (3.17–3.85) 2.29±0.03 (2.24–2.37) 18–22 21.70±4.43 (13.0–32.0) 68.29±6.93 (52.0–86.0) S. surdus / notes type II (1 male / 2 calls / 4 notes) Lebon Régis, SC – 1.12±0.05 (1.05–1.15) 3.69±0.17 (3.47–3.84) 2.40±0.02 (2.37–2.41) 8.75 ± 3.86 (5–14) 60.25±14.57 (44.0–74.0) 71.0±10.39 (58.0–82.0) S. caramaschii (1 male / 3 calls / 30 notes) Piraquara, PR 8.50±2.83 (5.23– 10.20) 0.94 ± 0.45 (0.11–1.57) 4.24 ± 0.40 (3.68–5.43) 2.62 ± 0.09 (2.49–2.76) 35.0±11.36 (22– 43) 0.54±0.01 (0.37–0.68) 220.9±44.3 (183–373) Tadpole. Unknown. Natural history. Males breed in the hot and rainy season of the year and call from the floating vegetation, generally in permanent ponds. The reproductive mode is probably number 1 ( sensu Haddad & Prado 2005 ): eggs and exotrophic tadpoles in lentic water. Geographic distribution. Besides the type locality, the species has also been collected in the municipalities of São Bento do Sul, Lebon Régis, Ponte Serrada, Urubici (based on advertisement call recordings), Lages, and Lontras, all in the state of Santa Catarina, and municipality of São José dos Ausentes, state of Rio Grande do Sul ( Figure 8 ).