Bioacoustics of Elachistocleis muiraquitan

Variation. SVL in males ranges from 26.8 to 32.7 mm , females from 30.6 to 39.7 mm , and the intensity of the color on throat has dark color, where in females it is immaculate. The females are larger than males ( Table 1 ). E. muiraquitan SVL HL HW Holotype male 31.8 6.0 7.2 Paratype males (n=7) 31.1 ± 0.9 (26.3–32.7) 5.9 ± 0.2 (5.2–6.5) 6.9 ± 0.2 (6.4–7.3) Paratype females (n=7) 33.5 ± 1.4 (30.6–39.7) 5.9 ± 0.2 (5.5–6.5) 7.0 ± 0.2 (6.4–7.5) E. helianneae (n=8) 26.5 ± 1.3 (24.7–28.4) 5.7 ± 0.4 (5.3–6.3) 6.4 ± 0.5 (5.5–7.2) E. matogrosso (n=20) 24.7 ± 2.6 (19.9–29.4) 6.2 ± 0.8 (4.7–7.9) 5.9 ± 0.7 (4.6–8.0) ED UEW IOD END IND HnL 2.0 1.0 3.6 2.6 1.7 7.3 2.0 ± 0.1 (1.7–2.3) 1.1 ± 0.1 (0.9–1.4) 3.6 ± 0.1 (3.3–4.1) 2.7 ± 0.1 (2.5–2.9) 1.8 ± 0.1 (1.5–2.1) 6.8 ± 0.2 (6.0–7.3) 2.0 ± 0.1 (1.7–2.3) 1.1 ± 0.1 (0.9–1.3) 3.7 ± 0.1 (3.5–4.0) 3.0 ± 0.1 (2.7–3.4) 2.1 ± 0.1 (1.7–2.6) 7.4 ± 0.2 (6.8–8.2) 2.0 ± 0.2 (1.8–2.4) 1.1 ± 0.2 (0.9–1.4) 2.8 ± 0.2 (2.6–3.0) 2.4 ± 0.3 (2.1–2.8) 1.9 ± 0.2 (1.7–2.2) 5.3 ± 0.5 (4.7–6.2) 1.8 ± 0.3 (1.1–2.3) 1.4 ± 0.5 (0.8–2.7) 2.6 ± 0.2 (2.3–3.0) 2.0 ± 0.3 (1.5–2.5) 1.6 ± 0.2 (1.1–1.9) 5.4 ± 0.4 (4.5–6.8) THL TBL FL 11.8 13.0 14.1 11.7 ± 0.5 (10.1–13.1) 12.4 ± 0.3 (11.3–13.4) 14.0 ± 0.4 (13.1–15.3) 12.9 ± 0.3 (12.5–14.1) 13.2 ± 0.3 (12.5–14.6) 15.3 ± 0.5 (14.5–16.7) 9.8 ± 0.5 (8.9–10.5) 10.6 ± 0.3 (9.8–11.0) 12.1 ± 0.7 (11.0–13.1) 9.1 ± 0.9 (7.0–11.7) 9.3 ± 1.0 (7.2–11.3) 11.3 ± 1.1 (9.0–13.0) Geographical distribution. Northern Brazil , in the southeastern of the state of Acre ( Fig. 3 ). Besides the type locality we found one specimen collected in the municipality of Rio Branco, Acre (ZUEC 5652) on 22 December 1983 ( Fig. 3 ). It is possible that this species is distributed over other areas of the Amazon. Natural history Notes. One adult female (SVL 39.7 mm ; 5.70 g without the ovules; ZUEC 5660) had its belly opened revealing 961 mature ovules ( 1.15 g ) in its ovaries. The estimated reproductive effort (as percentage of gonad mass in relation to body mass) was 20.2 %. Mature ovules presented a dark animal pole and a beige vegetal pole and had a mean diameter of 3.9 ± 0.17 mm ( 3.3 – 4.1 mm , n = 10). Call description. Nine advertisement calls of one male were recorded in downtown, Xapuri, Acre, on 22 December 1983 at 22:15 (FNJV 11823). Air temperature was 27ºC and water temperature 28ºC. The call consists of a loud, high pitched, sustained whistle, which can be divided in two parts ( Fig. 4 ). In the first part, the frequency is ascendant modulated varying from 2.76 ± 0.06 to 3.78 ± 0.07 kHz. In the second part the frequency is sustained (not modulated), and ranging from 3.36 ± 0.07 to 4.20 ± 0.02 kHz. The mean pulse rate is 195.69 per second and there are 802.34 pulses per call in average. Further spectral characteristics are presented in Table 2 . Initial and modulated portion of the call Final and sustained portion of the call Initial minimum frequency (kHz) Initial maximum frequency (kHz) Final minimum frequency (kHz) 2.76 ± 0.06 (2.61–2.92) 3.19 ± 0.04 (3.04–3.32) 3.18 ± 0.06 (3.06–3.34) Not applied Not applied Not applied Final maximum frequency (kHz) Duration (s) Minimum Frequency (kHz) Maximum Frequency (kHz) 3.78 ± 0.07 (3.64–3.99) 0.16 ± 0.01 (0.12–0.22) Not applied Not applied Not applied 3.94 ± 0.18 (2.86–4.42) 3.36 ± 0.07 (3.10–3.50) 4.20 ± 0.02 (4.13–4.28) Dominant Frequency (kHz) Not applied 3.78 ± 0.03 (3.75–3.93) Pulse duration (ms) Not applied 5.11 ± 0.13 (5.00–6.00)

Diagnosis. A small sized species (SVL 26.3–32.7 mm in adult males and 30.6–39.7 mm in adult females) characterized by the head length shorter than head width, HL about 84.7 % of HW; postcommisural gland poorly developed; dorsum smooth; in preservative uniformly dark brown with a thin middle longitudinal light stripe from the post-cephalic transverse skinfold to the vent, but absent on the head; venter immaculate; limit between the dorsal and ventral regions well defined; a broad irregular line on the posterior surface of the thighs; a large light spot on the proximal internal surface of tibiae; a narrow light stripe surrounding the knees and reaching the middle of the tarsus. Comparisons with other species. For comparison between species we followed the taxonomic characters (external morphology and bioacoustics) currently used for the genus Elachistocleis (see Caramaschi 2010 ; Toledo 2010; Toledo et al. 2010). Elachistocleis muiraquitan distinguishes from E. bumbameuboi , E. carvalhoi , E. cesarii , E. erythrogaster Kwet and Di-Bernardo , E. magnus , E. piauiensis Caramaschi and Jim , E. skotogaster Lavilla, Vaira and Ferrari , E. surinamensis (Daudin) and E. surumu by presenting an immaculate venter (vs. spotted in the other species). This character did not show intraspecific variation in the examined specimens. From the only three species with immaculate venter, E. matogrosso , E. bicolor (Guérin-Méneville) and E. helianneae , the new species is readily distinguished by presenting a longer head (HL about 84.7 % of HW in E. muiraquitan ; 90 % in E. bicolor , 92 % in E. matogrosso and 94.6 % in E. helianneae ), by the presence of the light and merged mid-dorsal stripe from the post-cephalic dermal fold to vent (mid-dorsal stripe absent in E. bicolor , mid-dorsal stripe from the tip of snout to vent in E. helianneae ) and by the absence of minute light spots on dorsum and dorsal surfaces of members (present in E. helianneae ). From E. matogrosso it also distinguishes by the larger SVL size (males of E. matogrosso are smaller than 25 mm and males of E. muiraquitan are larger than 30 mm ) and by the lower frequency advertisement calls, in E. matogrosso the frequency of the advertisement call varies from 2.88 to 4.79 kHz, and the dominant frequency is 4.15 kHz (based on Nunes et al. 2011 : calls recorded at type locality); and in E. muiraquitan it varies from 2.61 to 4.28 kHz and the dominant frequency is 3.84 kHz. The PCA was able to distinguish E. muiraquitan from the two morphologically closest species, almost without overlap in the first component (Factor 1), which explained most of the variation ( Fig. 2 ). Factor 1 is mostly influenced by THL, TBL, and FL (contributing with about 13 % of the variation), SVL, IOD, and END (contributing with about 12 % of the variation). Other variables contributed with less than 10 % of the variation. When plotting Factor 1 against Factor 2 we observed two groups of E. matogrosso , which includes individuals of the same populations, indicating larger intraspecific variation for this species ( Fig. 2 ). Variation in Factor 2 is mostly influenced by UEW (27 %) and HL (24 %).