Bioacoustics of Aromobates saltuensis

Diagnosis. (1) Skin on dorsum smooth to finely granular. (2) Paired dorsal scutes present on digits. (3) Distal tubercle on FIV present. (4) FIV length reaches half distal subarticular tubercle of finger III. (5) FI longer than II. (6) Digital discs present. (7) Finger discs weakly expanded. (8) Finger fringes mainly absent. (9) Metacarpal ridge absent. (10) FIII not swollen in adult males. (11) Carpal pad absent. (12) Male excrescences on thumb absent. (13) Thenar tubercle present, small. (14) Black arm gland in adult males absent. (15) Tarsal keel thick, long, to mid-tarsus, straight, ending tubercle-like. (16) Toe discs moderately expanded. (17) Toe webbing reduced. (18) Metatarsal fold absent. (19) External coloration with pale dorsolateral stripes; ventrolateral stripe absent; oblique lateral stripe formed by a series of diffuse yellow and white spots. (20) Gular-chest markings present but indistinct on males, absent on females. (21) Dermal collar absent. (22) Male throat coloration grey with profusion of melanophores; female throat coloration dirty white with a profusion of melanophores. (23) Male abdomen color immaculate white. (24) Female abdomen color dirty white. (25) Iris coloration bronze with black reticulation; pupil ring bronze. (26) Large intestine unpigmented. (27) Testes white. (28) Median lingual process absent. (29) Tympanum distinct in its inferior half, tympanic annulus absent. (30) Vocal sac distinct. (31) Teeth present on the maxillary arch. (32) Size small, males ( n = 3) 22–23.1 mm , mean 22.6 ± 0.6; females ( n = 3) 22.9–26.9, mean 25.5 ± 2.3. Varitation in the referred series. Rivero (1978) described variation within A. saltuensis by confronting the type specimen against a subadult (UPRM 5593) also collected from the type locality. However, the description provided in Rivero (1978) does not allow us to unambiguously evaluate the variation among our referred series. Therefore, we provide a description of the variation only based on our referred series. Males have a SVL range of 22–23.1 mm , and females SVL range of 22.9–26.9 based on three adult specimens of each sex. Body is slender, round to quadrangular in cross-section. Dorsal skin, including dorsal surfaces of hind limbs is smooth, shagreen to finely granular, without tubercles on the posterior part of the body in preservative. Ventral skin is smooth. Head is longer than wide, HeL = 35.8–37.9 % SVL; HW = 32.8–36.3 % SVL. On males, snout is truncated to pointed in profile. On females, snout is rounded to slightly pointed. Nares are situated laterally to the tip of snout; narial openings are barely visible when viewing the head from the front, not visible when viewing dorsally; and they are visible when viewing from a ventral perspective. Canthus rostralis is angular, the loreal region is almost flat; interorbital region is little wider than the upper eyelid. Snout is longer than ED. Only half of the tympanum is distinct and it is visible at its anteroventral portion but concealed posterodorsally by a low supratympanic bulge formed by the superficial slip of m. depressor mandibulae . The tympanum is positioned closely behind eye and close to the angle of jaws. Teeth are present on maxillary arch. Vocal slits are short to long, arched from mid-level of tongue to the anterior angle of the jaws. The tongue is short, oval to triangular; it is half free posteriorly. Hand is of moderate size (25–28.2 % SVL); relative lengths of adpressed fingers are III> I> II> IV; discs of all fingers are weakly expanded, horizontally oval to round; FIII is barely wider than distal end of adjacent phalanx, at its maximum point is 1.3 wider; the base of palm has a large, palmar tubercle, rounded, quadrangular to heartshaped; and on the base of FI there is a smaller (approximately 1/3 of the palmar tubercle), oval to elongate thenar tubercle; one or two subarticular tubercles on fingers (one each on FI and FII, two each on FIII and FIV); and all tubercles are flat to round or oval; without supernumerary tubercles. Fringes on fingers are mainly absent, but on some males and females can be present, they are low and indistinct on FII and FIII. Hind limbs are of moderate length, SL = 47.5–52.9 % SVL; relative lengths of adpressed toes are IV> III> V> II> I; TI is short, the tip never reaching the mid-subarticular tubercle of TII; toe discs are round to oval, moderately expanded, TIV is about 1.8 times wider than distal end of adjacent phalanx; feet is moderately webbed; formula is I2-2 ½ II2-3 ½ III3-4 IV and basal between TIV and TV; fringes on all toes are notable, short but flap-like with a folding around the toes; one to three non-protuberant, subarticular tubercles are present but small (one on TI and TII, two on TIII and TV, three on TIV, proximal one almost indistinct); two metatarsal tubercles are present, including a small rounded outer, and a slightly larger oval inner tarsal tubercle; mid-tarsal tubercles are seldom seen; tarsal keel is well-defined, thick, straight, transverse across tarsus, from proximal edge of inner metatarsal tubercle to mid-tarsus, with an ending tubercle-like structure; cloacal opening is located at the upper level of thighs, with short tube flap or anal sheath. Comparison with the original description. When compared with the original description ( Rivero 1978 ), we found a few additional details that should be noted. First, Rivero (1978) does not note a supratympanic bulge, but this characteristic varies depending on the preservation method. Second, Rivero also mention the presence of basal webbing between FII-III-IV, which is absent on the referred specimens examined (another character that can vary in preserved specimens). All the remaining characteristics described for the holotype are among the variation seen in the new specimens collected. Color. The referred specimens in life have dorsa with pale to dark brown coloration, patternless or presenting irregular spotting; the dorsolateral stripes can be very distinct ( Fig. 10 A) to ill-defined ( Fig. 10 C), pale orange to dark brown. The flanks can have a narrow dark brown longitudinal band below the dorsolateral stripe or they can be completely dark brown to the ventral area. The oblique lateral stripe can be solid, diffuse, or almost absent (consisting in a few, irregular and indistinct dirty white spots in the inguinal zone, even not forming a real stripe). Upper lips are patternless. Arms and hind limbs can be pale orange or brown to dark brown, with darker well-defined to ill-defined crossbars. Ventrally, males are pale grey on the throat and chest, white on the belly, with some opaque yellow on the hind limbs ( Fig. 10 B). Females are plain grey on the throat, dirty white on the belly ( Fig. 10 D). Iris is bronze with black reticulation; iris ring is also bronze. Preserved specimens have a minimal dichromatism slightly apparent ventrally on males, as they have darker throats (pale to dark grey), consisting of a profusion of melanophores under magnification. Females are all white (with a few melanophores under magnification). The rest of the body coloration is not dichromatic in both sexes, varying in being paler or darker, with well or ill-defined crossbars on hind limbs. Natural history. We found all Aromobates saltuensis associated to a slow flowing creeks surrounded by pastures ( type locality), primary, and secondary forests (Rio Frio, Tamá). Several males were calling from exposed and concealed sites in the creek, such as on the top of rocks or behind small waterfalls. Some females were seen moving along the creek as well. All individuals were active during daytime. Vocalization. The analyzed call is a section of a trill that lasted several minutes. The call was recorded at 22.5ºC (water temperature) at early afternoon on the June 9th, 2007 near the type locality (see referred specimens). The analyzed section of the call has four duplets of notes ( Fig. 11 ), lasting 2 sec. One to two duplets of notes are produced per second. The dominant frequency of the first pulse is slightly lower than the second. The first pulse has a dominant frequency range of 3437.0–3862.7 Hz. The second pulse has a dominant frequency range of 3511.0 –3862.0 Hz. Four consecutive duplets were chosen at random from the spectrogram to determine temporal variables. Duplet duration 0.15 ± 0.01 (0.14–0.16) seconds, and inter-duplet interval 0.46 ± 0.17 (0.34–0.65) seconds. Note and inter-note duration with their mean, SD and range in seconds are indicated as follows (1) note duration, first note 0.04 ± 0.01 (0.03–0.04); second note 0.05 ± 0.01 (0.04–0.05); and (2) inter-note, 0.07 ± 0.01 (0.06–0.07). Both, the waveform is shown by Fig. 11 A and the spectrogram by Fig. 11 B.