Hemiphractus scutatus (Spix, 1824)

Moraes, Leandro João Carneiro de Lima & Pavan, Dante, 2018, On the occurrence of Hemiphractus scutatus (Spix, 1824) (Anura: Hemiphractidae) in eastern Amazonia, Amphibian & Reptile Conservation (e 151) 12 (1), pp. 5-14 : 7-9

New records of Hemiphractus scutatus

We found three specimens of H. scutatus in two of the 11 sampling sites ( Figs. 1–3). It was a rare species in the sampling, recorded at a ratio of one specimen in about each 300 days of sampling, while the most abundant syntopic terrestrial frogs were from genera Adenomera Steindachner, 1867 , Pristimantis Jiménez de la Espada, 1870 , Allobates Zimmermann and Zimmermann, 1988 , and Rhinella Fitzinger, 1826 , with 2,700 specimens recorded in this same sampling effort. The three specimens of H. scutatus were only recorded by the active searches, and exclusively in Terra Firme forests ( Fig. 4).

On 28 September 2012 one female voucher specimen was collected by D. Pavan close to a large tree and under a palm leaf, on the left bank of Tapajós River , at 19:15 h (76.1 mm SVL; 05°02’S, 56°53’W, 62 m above mean sea level, hereafter referred as asl). On 16 October 2012 a male voucher specimen was collected on the same riverbank by LJCL Moraes hidden inside the leaf-litter at 21:05 h, distant ca. 51 km in straight line from the first record (57.8 mm SVL; 04°39’S, 56°37’W, 60 m asl). On 28 April 2013 a second female voucher specimen was collected also hidden inside the leaf-litter on the same riverbank by J. Cassimiro at 21:30 h (61.7 mm SVL; 04°40’S, 56°37’W, 83 m asl), distant ca. 50 km in straight line from the first record and 430 m from the sec- ond record. No evidence of reproductive activity or gaping posture ( Trueb 1974) was observed .

These three records represent the easternmost known localities of occurrence of H. scutatus , extending the geographic range of the species and the genus Hemiphractus . They are distant ca. 1,000 –1,500 km from the previously known easternmost points of the species occurrence, in Rondônia ( INPA-H 15398, 15399) and Amazonas States, Brazil ( GBIF 2017; SpeciesLink 2017) ( Fig. 1). Considering only the Amazon Basin at South of Amazon River, these new records even extend to the East the geographic range of the family Hemiphractidae . Furthermore, the elevation level in which these specimens were recorded are among the lowest known elevation for the species (60, 62, and 83 m asl; Fig. 5), and two of them (60 and 62 m asl) also extend downwards the known elevational range of this species, since there are no documented records of individuals below 70 m asl.

Morphologic variation and molecular relationships

The morphologic data confirms the identification of our specimens in accordance to the literature ( Trueb 1974) and voucher specimens. Qualitative characters include the triangular head, canthus rostralis rounded in section; tympanum large and vertically ovoid; oblique rows of tubercles on dorsal surfaces of forearm and hind limb (less pronounced in female specimens); small triangular fleshy proboscis, dorsoventrally flattened, on tip of snout; eyelids granular with one (female specimens) or three (male specimen) prominent fleshy conical tuber- cles; single bony projection at the angle of the jaw; slightly enlarged tubercles at the knee and small tubercles at calcaneum (divergent from the absence of calcar projections reported by Trueb 1974 and Rodríguez and Duellman 1994); fingers and toes with vestigial adhe- sive discs, well-developed round subarticular tubercles and basal webbing; thenar tubercle elliptical and outer palmar tubercle diffuse, flat and cordiform; no evidence of nuptial pads in male specimen; toes also with well-developed round subarticular tubercles and about onefourth webbed; inner metatarsal tubercle well-developed and elliptical, and outer metatarsal tubercle indistinct; shagreened skin on dorsum and granular on flanks, abdo- men and ventral surfaces of thighs.

Dorsal coloration in life varies from reddish brown ( INPA-H 38116 and 38118) to pale tan background with dark mottling ( INPA-H 38117), with two dark vertebral spots; dark suborbital marks from the lower margin of the eye expanding posteroventrally but not reaching the lip (more pronounced in INPA-H 38117 than in INPA- H38116 and 38118) and scattered dark spots in the tympanic region. Ventrally, gular coloration varies from uniformly brown ( INPA-H 38116 and 38118) to mottled ( INPA-H 38117), with a pale mid-ventral stripe reaching the pectoral region; same gular color reaches the pectoral region, and becomes less pigmented posteriorly. A finely dark venate pattern covers the flank areas above the forelimb; forelimbs and hind limbs varies from uniformly brown ( INPA-H 38116 and 38118) to tan (INPA- H38117), with dark transverse bands, reaching the dorsal surface of hands (more evident in INPA-H 38117); iris bronze and darker ventrally, with a longitudinally crossing reddish area and pupil horizontal. Regarding quantitative characters, most of the measurements of the middle Tapajós River specimens agree with the known morphometric range of the species ( Table 1), also showing the sexual dimorphism in body size. The only divergence is a small HW compared to SVL in female INPA-H 38116.

The 16S mtDNA tree for Hemiphractus species shows, as the results presented by Castroviejo-Fisher et al. (2015), two distinct lineages of H. scutatus . The middle Tapajós River population is more related to the lineage from Peru ( Figs. 6, 7), as the sequences have a higher genetic similarity (more than 97%) compared to sequence from Colombia, near the country’s border with Brazil (93%) ( Fig. 7).