Bioacoustics of Ischnocnema lactea

Color in preservative . Background color in preservative faints into different tones of gray and silver. Our observations of old-dated fixed specimens revealed that hidden surfaces become slightly opaque, maintaining the same colors, while patterns and bright colors disappear with time. In general, all specimens maintained the former pattern of blotches, dots, and stripes in all surfaces. Geographic distribution . Ischnocnema lactea is endemic to the Atlantic Rainforest biome, occurring in central portion of Serra do Mar , in the State of São Paulo , Southeastern Brazil . It inhabits mountainous forests at moderate altitudes, occurring from 700–1,120 m a.s.l. ( Fig. 6 ). Coordinates of localities are provided in Appendix 2. Vocalization and acoustic comparisons. The advertisement call of Ischnocnema lactea consists on a single pulsed note (notes emitted in series in I. nigriventris and I. randorum ), containing from eight to thirteen pulses ( Fig. 7 ). The mean dominant frequency is 2418.9 ± 17.9 Hz (2239.5–2756.2 Hz, N = 24 notes). The mean note duration is 908 + 144 ms (634–1060, n = 24 notes). The mean of pulses per note is 10.45 + 1.10 (8–13, n = 24 notes), and note rate of 11.01 + 3.77 notes per minute (6.77–14.29, n = 24 notes). The mean of pulse duration is 6.5 + 1.2 ms (3.3–9.5 ms, n = 251 pulses). The mean of pulse rate is 113.83 + 12.45 s (94.33– 138.88 s , n = 24 pulses). The interval between pulses is evident mainly between the first and second pulses, on average 4.79 + 1 ms (3.53– 6.96 ms, n = 19 pulse intervals). The amplitude modulation between the other pulses is usually incomplete, i.e., there is no evident silence between them. The advertisement call of Ischnocnema lactea differs other species of its series by having pulses. Moreover, its call duration is longer than those of I . nigriventris and I . vizottoi , and shorter than that of I . randorum . Additional comparisons are provided in Table 2 . I. lactea I. nigriventris I. randorum I. vizottoi Number of notes/call 1 2–4 3–8 1 Call duration (ms)* 635–1060 194–565 2000–5000 – Call rate (Calls/min.)* 6.77–14.29 – 0.1–0.2 9.5 2.2 Note duration (ms) 635–1060 28–88 40–100 38–72 Pulses per note 8–13 – – – Dominant frequency (Hz) 2240–2756 1955–3932 3800–5200 2780–3555 References Present work Berneck et al . (2013) Heyer (1985) Martins and Haddad. (2010) * For Ischnocnema lactea . call = note. Natural History . The reproductive activity of I. lactea occurs during winter season (May-September) and appears to be associated with cold fronts that cause sudden drops in temperature along with rain, drizzle, and fog. Males call mainly during the day, starting early in the morning at around 07h00 a.m., decreasing the intensity at about 08h00 p.m. On one occasion, a male was recorded vocalizing until 09h00 p.m. Males vocalize perched on herbaceous vegetation, shrubs, and vertically on tree trunks in varying elevations ( 0.50–2 m , N = 8), and usually become darker when they are calling. Out of breeding season they become uncommon, and are rarely observed moving around on the leaf litter or resting on vegetation both during the day and at night. Two reproductive events were observed: the first occurred on 22 June 2010 at PNMNP (Vivian Trevine pers. comm.) during the arrival of a cold front, when ca. 200 males started calling in the morning from the litter (mainly) and shrub vegetation. Four to five pairs in amplexus ( Fig. 8 ) were collected in pitfall traps . In the afternoon of the same day, the calling activity had already declined considerably, decreasing much more on 23th, the last day of the survey. The weather on 22 June , at 9:45 a.m. exhibited the following conditions: temperature 15.5o C, 84% humidity, cloudy, drizzling to light raining with fog; 23 June , at 8:30 a.m., temperature 14.4o C, 86% humidity, cloudy weather. The second event occurred on 15 June 2015 at the Núcleo Curucutu of PESM, in the municipality of São Paulo. About 150 males started vocalizing in the morning and continued through the afternoon, between 07h00 a.m. and 05:00 p.m., with a decrease of call activity after 04:00 p.m. The weather conditions consisted on a temperature varying between 12.1– 13.7°C, humidity 96–100%, cloudy with fog and drizzle.