Bioacoustics of Pseudopaludicola hyleaustralis

Description of holotype . Snout rounded both in dorsal and lateral views; head longer than wide; tympanum indistinct; nostrils slightly protuberant, directed anterolaterally; pupil horizontally elliptical; vomerine teeth absent; tongue ovoid, covering the entire floor of mouth and posteriorly free; vocal sac single, subgular. Surfaces of dorsum, venter, upper eyelids, belly and throat smooth. Arms robust, with two subconical antebrachial tubercles, the distal one scarcely perceptible; fingers free, relative lengths IV<I<II<III; inner metacarpal tubercle oval; outer metacarpal tubercle rounded; subarticular finger tubercles enlarged, rounded; thumb with a fine nuptial asperity on the base; supernumerary finger tubercles small, rounded. Hindlimbs robust, long; thigh longer than shank, foot longer than thigh; a well developed dermal fold from the inner metatarsal tubercle to mid length of tarsus; thickening of the distal end of this tarsal fold resembles a tubercle; toes basally webbed, relative lengths I<II<III<V<IV; inner metatarsal tubercle oval; outer metatarsal tubercle rounded; subarticular toe tubercles enlarged, rounded, supernumerary toe tubercles absent. Color. In life ( Figure 3 A–B), dorsum and limbs are brown, with either green and brown spots or stripes. Belly white; ventral view of legs yellowish white and vocal sac beige with dark dots; iris reddish-brown superiorly and grayish-brown inferiorly; upper lip with vertical wide green stripes (see Figure 3 ). In preservative, dorsum and dorsal surface of limbs grayish brown with dark brown spots or stripes; belly and ventral surface of legs light beige; vocal sac grayish. Variation. Sexual size dimorphism is apparent, with females attaining larger size than males ( Table 1 ). Adult males have a beige vocal sac, either unpigmented (in 55.8% of the 29 examined males) or with grayish vermiculations (44.2%). Dorsal coloration is highly variable, from light brown to dark gray, with nearly one third of the specimens (35.2% of the 35 examined specimens) presenting a pair of lateral light stripes from the eyes to the groin. Ventral coloration is light beige, either unpigmented (55.8% of the examined specimens) to heavily pigmented (26.4%), with some specimens (17.8%) presenting an unpigmented light beige belly but pigmented vocal sacs and ventral surfaces of thighs. Only one specimen out of 35 (UFMT 8275) has a thin vertebral stripe from the tip of the snout to vent. Pseudopaludicola hyleaustralis Pseudopaludicola canga Marabá Curionópolis Male paratypes Female paratypes Males Females Males Holotype (N=29) (N=6) (N=6) (N=5) (N=6) Snout-vent length 15.9 14.3±1.1 15.4±1.7 15.2±0.63 18.2±1.85 15.7±0.6 (12.2–16.1) (13–17.5) (14.6- (15.5-20.1) (14.6-16.5) 16.2) Head width 5.3 4.8±0.5 5.3±0.5 5.4±0.53 6.1±0.52 5.3±0.2 (3.7–5.8) (4.4–5.7) (4.6-6.0) (5.4-6.6) (5–5.6) Head length 6.1 5.3±0.5 5.7±0.8 4.8±0.24 5.3±0.36 6.3±0.3 (4.5–6.1) (4.6–6.5) (4.5-5.1) (4.9-5.9) (5.8–6.8) Tibia length 6.7 6.9±0.6 7.1±0.5 7.6±0.46 8.3±0.78 7.7±0.3 (5.8–8.0) (6.6–7.9) (7.1-8.3) (7.1-9.3) (7.3–8.0) Thigh length 7.1 6.8±0.5 7.4±0.6 7.9±0.3 8.9±0.58 7.1±0.4 (5.9–7.7) (6.8–8.5) (7.4-8.2) (8.3-9.5) (6.5-7.5) Foot length 8.4 7.8±0.6 8.1±0.3 8.6±0.51 9.2±0.72 8.4±0.4 (6.8–8.9) (7.1–8.5) (7.8-9.1) (8.1-9.9) (7.9-9.0) Hand length 4.2 3.9±0.4 4.1±0.3 4.4±0.38 4.5±0.5 4.0±0.2 (3.3–4.7) (3.7–4.5) (3.7-4.7) (4.0-5.2) (3.8-4.4) Eye diameter 2 1.9±0.2 1.9±0.2 2.2±0.22 2.2±0.24 1.8±0.1 (1.5–2.3) (1.7–2.1) (2.0-2.6) (2.0-2.5) (1.8-1.9) Eye–nostril 1.3 1.4±0.2 1.3±0.1 1.3±0.14 1.5±0.12 1.7±0.1 distance (1.2–1.8) (1.1–1.4) (1.1-1.4) (1.4-1.7) (1.6-1.9) Geographic distribution. Pseudopaludicola hyleaustralis is known from four localities in the northern state of Mato Grosso, Brazil (municipalities of Colniza, Alta Floresta, Nova Bandeirantes, and Aripuanã), along the drainages of the Apiacás, Roosevelt and Aripuanã rivers ( Figure 1 ). Natural history notes. Males of Pseudopaludicola hyleaustralis at Alta Floresta and Nova Bandeirantes were found calling in the evening, until 20:00 h. Males call from the ground, in shallow water with sandy or muddy substrates, in open areas surrounded by primary forest. The single specimen from Aripuanã was found during the day, on the muddy bed of a tiny intermittent tributary of the right bank of the Aripuanã River. At Alta Floresta, couples in axillary amplexus ( Figure 3 B) were observed in January, during the peak of the rainy season. Conservation . In most of the localities aforementioned, populations of Pseudopaludicola hyleaustralis are under strong pressure due to habitat destruction. In the municipalities of Alta Floresta, Aripuanã, and Nova Bandeirantes, the main causes of habitat loss are due to the construction of hydroelectric power plants, selective logging, and mineral exploration. The situation seems to be better at Colniza, where some populations might be protected in the 800 km 2 of the federal conservation unit "Estação Ecológica do Rio Roosevelt". FIGURE 4. Oscillogram and audio spectrogram of the advertisement calls (14 notes) of Pseudopaludicola hyleaustralis sp. nov. (UFMT 5560), recorded on 10 January 2007 in the Apiacás River, Alta Floresta, Mato Grosso, Brazil (19:00 h, air temperature 24ºC). Description of the advertisement call. We analyzed 135 calls of two specimens of Pseudopaludicola hyleaustralis ( holotype UFMT 5560; paratype UFMT 5561), both recorded at Alta Floresta, Mato Grosso, Brazil . A typical advertisement call of the new species consists of call series composed of 11–74 (43.3±18.7) non-pulsed notes (Figure 4), with a mean call series duration of 4.25± 2.2 s (range 1.14–8.15), emitted at regular intervals of 46.78± 11.63 s (29.73–58.79). Mean duration of each note is 0.03± 0.003 s (0.025–0.049). Each note is followed by internote intervals of 0.078± 0.022 s (0.035–0.171) and the average rate of notes per minute is 561.45±44.5 notes/ min (503.76–623.21). Mean frequency ranges from 3540–4379 Hz, and mean dominant frequency is 3938±158.65 Hz (3605–4165.3). Each note has a slight ascendant frequency modulation in its first half, and another ascendant frequency modulation in its last half.

Diagnosis. Pseudopaludicola hyleaustralis sp. nov. is assigned to the genus Pseudopaludicola based on the presence of hypertrophied antebrachial tubercle ( Lynch 1989 ; Lobo 1995 ). The species cannot be assigned to the P . pusilla group, due to the absence of T-shaped terminal phalanges ( Lynch 1989 ). In the genus, Pseudopaludicola hyleaustralis sp. nov. can be considered a medium-sized species, characterized by the combination of the following characters: (1) SVL 12–16 mm in males and 13–17 mm in females, (2) snout rounded both in dorsal and lateral views, (3) upper eyelids smooth, (4) toe tips not expanded laterally, (5) advertisement call composed of non-pulsed notes emitted in series of 11–74 notes, (6) note duration 0.03– 0.05 s, (7) mean dominant frequency of advertisement call 3938±158.65 Hz (3540–4379). Comparison with other species. Pseudopaludicola hyleaustralis sp. nov. can be distinguished from all congeneric species belonging to the P . pusilla group ( P. boliviana , P . canga, P. ceratophyes , P . llanera, and P . pusilla ) by the absence of either T-shaped terminal phalanges or expanded toe tips (disks or pads). The new species can also be differentiated from selected members of this group by the following characters (characters of compared species in parentheses): from P . boliviana , P. ceratophyes , and P. llanera , by the absence of palpebral tubercles (tubercles evident on upper eyelids; Lynch 1989 ); from P. ceratophyes , by the presence of toes only basally webbed (toes approximately 1/2 webbed; Rivero & Serna 1984 ; Lynch 1989 ); from P . pusilla and P. l l a n e r a , by the snout rounded in dorsal view (snout subacuminate and acuminate, respectively, in dorsal view; Lynch 1989 ); from P . canga , by the absence of dorsal folds (presence of dorsal folds; Giaretta & Kokubum 2003 ).