Rhinella magnussoni Lima, Menin & Araújo, 2007, sp. nov.

Rhinella magnussoni, sp. nov.

(Figures 1–3)

Holotype. INPA-H 19543, adult male, Brazil, Pará, near Santarém city, Belterra municipality, Highway 163, Km 89 (03.15313°S, 54.84216°W), in leaf litter, February 2006, by Albertina P. Lima.

Paratypes. Males, INPA-H 19529, 19531, 19544, 12–13 February 2004, INPA-H 19527, 19528, 19530, 19532, 19536–19542, 19546, 19547, 18–27 February 2006; females, INPA-H 19525, 19526, 19533–19535, 19545, 18–27 February 2006, by Albertina P. Lima, Maria C. Araújo and Edivaldo F. Vasconcelos, same locality as holotype.

Diagnosis. This new species is included within the Rhinella margaritifera group, with the following combination of characters: (1) size of adult males in type series 36.0– 45.3 mm SVL, adult females in type series 43.1–53.3 mm SVL, (2) snout pointed in dorsal view, protrunding beyond margin of lip, (3) nostril lateral, protuberant, (4) canthal crest not raised, (5) supraorbital crests not developed, (6) supratympanic crest prominent, (7) supraorbital and supratympanic crests continuous, both with tubercles, (8) tympanic membrane distinct, (9) bony protrusion at angle of jaws, (10) parotoid glands small and not very distinct, (11) upper eyelid without projections, (12) presence of a dorsolateral line of tubercles that extends from behind the eye along the side to the base of the legs, (13) neural crests of vertebrae absent, (14) skin on dorsal, dorsolateral and ventral surfaces with spicules in males and females, (15) first finger shorter than second finger, (16) rudimentary lateral fringes on both sides of all fingers, except the outer edge of finger III, (17) a line of spinose tubercles on all lateral fringes except on the outer edge of finger IV, (18) all toes webbed in males and females, (19) lateral fringes present on all toes in females and all but the fourth toe in males, (20) nuptial excrescences present in the first two fingers of males (all these characteristics can be seen in Figs. 1, 2, or 3).

Rhinella magnussoni is distinguished from R. acustirostris, R. ceratophrys, R. dapsilis, R. hoogmoedi, R. proboscidea, R. roqueana, R. sclerocephala, R. stanlaii and Rhinella sp. 1 by smaller SVL; from R. castaneotica and R. cristinae by the greater SVL in males; from R. acutirostris, R. ceratophrys, R. hoogmoedi, R. margaritifera, R. roqueana, R. sclerocephala, R. stanlaii and Rhinella sp. 1 by absence of well developed cephalic crests (versus presence); supratympanic crests not forming a expanded bony projection (present in R. margaritifera and R. sclerocephala); from R. acutirostris and R. alata by the presence (versus absence) of a bony protrusion at the angle of the jaws; from R. ceratophrys by absence (versus presence) of a prominent, triangular dermal projection on the outer edge of the eyelid; from R. ceratophrys, R. cristinae, R. iserni, R. margaritifera, R. roqueana, R. sclerocephala and Rhinella sp. 1 by the absence (versus presence) of vertebral neural spines protruding through the skin on the back; from R. castaneotica, R. dapsilis, and R. proboscidea by skin on dorsal, dorsolateral and ventral surfaces with spicules in males and females (dorsal surface smooth in males of R. castaneotica and R. proboscidea and in females of R. dapsilis); from R. dapsilis by the absence (versus presence) of a prominent soft fleshy proboscis on the end of the snout; from R. proboscidea by the snout pointed but not extending far beyond the nostrils (snout pointed extending far beyond the nostrils in R. proboscidea) and by the presence (versus absence) of a dorsolateral line of tubercles; from R. scitula by the snout pointed in dorsal view and small parotoid glands (snout rounded in dorsal view and parotoid glands large and globular in R. scitula); from R. ceratophrys, R. cristinae and R. iserni by the evident tympanum (tympanum absent in this species); from Rhinella sp. 2 by its slightly greater size and by the absence (versus presence) of tuberculated margins of external regions of feet and toes (see Melin 1941; Myers & Carvalho 1945; Duellman 1978; Hoogmoed 1986, 1989; Caldwell 1991; Rodríguez & Duellman 1994; Lötters & Köhler 2000; Mijares-Urrutia & Arends 2001; Vélez-Rodriguez & Ruiz-Carranza 2002; Caramaschi & Niemeyer 2003; Caramaschi & Pombal 2006; Lima et al. 2006; Fouquet et al. in press).

Description of the holotype. Measurements are provided in Table 1. An adult male, head length 93 % of head width, head width 34 % of SVL; snout pointed from above (Fig. 1 a), with a distinct vertical, fleshy ridge, running from the tip of the snout to the mouth; snout acute in lateral profile expanding beyond margin of lip (Fig. 1 a and e); snout 45 % of head length; internarial distance 23 % of head width; dorsal surface of snout and head weakly depressed; canthus rostralis barely concave; loreal region concave; nostril lateral, protuberant, closer to tip of snout than eyes; internarial distance about the same as distance from eye to nostril; eye-narial distance smaller than eye diameter (Fig. 1 a and e); tympanum distinct, ovoid, smaller than eye diameter (Fig. 1 e); canthal crest not raised; supraorbital and postorbital crests not developed continuous with prominent supratympanic crest; parotoid gland not well developed, slightly triangular in dorsal view, expanding laterally; lateral row of tubercles from posterior margin of parotoid gland to base of the leg; well developed bony protrusion at angle of jaws; skin on dorsal, dorsolateral and ventral surfaces with spicules; mid-dorsum and area between eyes relatively smooth; skin of belly tubercular, partly with conical tubercules (Fig. 1 a, b and e). Forelimbs robust, skin granular, forearms less robust then arms; forearms with a brown band on ventral surface. Hand (Fig. 2 c) with rudimentary basal webbing between fingers, more developed in females (Fig. 2 a); relative length of fingers I <II = IV> III; tips of fingers on inferior surface globular and swollen; rudimentary lateral fringes on both sides of all fingers, except the outer edge of finger III; a line of spinose tubercles on all lateral fringes except on the outer edge of finger IV (Fig. 2 c); palmar tubercle prominent, ovoid; thenar tubercle rounded; subarticular tubercles well developed, single; supernumerary tubercles of different size, rounded, distributed irregularly on palm, different when compared with those of females (Fig. 2 a and c); nuptial excrescences on the dorsal surface of fingers I and II (Fig. 1 a). Hindlimbs short, dorsal surface of skin granular; tarsus with a brown band on ventrolateral surface; tibia length 37 % of SVL. Foot (Fig. 2 d) with basal webbing between toes, more developed in females (Fig. 2 b); lateral fringes of all toes with a line of spinose tubercles, more developed in females (Fig. 2 b); relative length of toes I <II <III <V <IV; inner metatarsal tubercle distinct, ovoid; outer metatarsal tubercle small, rounded, about half the size of inner; subarticular tubercles rounded, single; supernumerary tubercles of different size, rounded, distributed irregularly on plantar surface, different from those of females (Fig. 2 b and d). Colour in preservative: dorsum red brown with diminutive dark brown spots on spicules (Fig 1 a); a pale mid-dorsal fine line from snout to cloaca; row of dark brown tubercules extends laterally from behind the eye to the base of the legs; chest dark brown; throat with irregular small spots; irregular cream spots with dark brown frames on ventral surface (Fig. 1 b); posterior belly uniformly light brown; cloacal region borded by cream and dark brown spots; irregular lateral dark brown band on proximal lower surface of forearms, hand, foot and tarsus (all the above information can see on Figs. 1 a and b). Color in life similar to that in preservative, however, more intense. Iris in life gold with black reticulations (Fig. 1 e and f).

Variation within type series. The type series includes 17 males and six females. The dorsal surface coloration is variable (Fig. 3). Five of these individuals (22%) have a wide mid-dorsal stripe, one individual has a fine mid-dorsal stripe and one individual (holotype) has a very narrow mid-dorsal stripe; 17 (74 %) have no mid-dorsal stripe. Twelve individuals (52 %) have an inter-ocular stripe. Two females and one male have a more rounded tympanum than the others, which have oval tympani. A distinct vertical, fleshy ridge, running from the tip of the snout to the mouth is more developed in larger males. Five males have less developed lateral rows of tubercles than the other individuals. The ventral surface coloration is variable (Fig. 3); 17 individulas (74 %) have bellies with whitish to cream spots with dark brown or grayish frames, three (13 %) have cream bellies without irregular spots; one individual has a cream belly with small irregular dark brown spots; one individual has a gray belly with irregular cream markings posteriorely. Colour in preservative and life are similar. Sexual dimorphism is indicated by males having smaller size (Table 1), and nuptial excrescences on fingers I and II.

Advertisement call. The calls of 14 males were recorded between 18 and 27 February 2006 at temperatures varying from 22.8 to 29.4 o C (Table 2). The call of the new species is formed by one note emitted in discrete call series. The notes within each call series were separated by similar intervals (Fig. 4). The call series were alternated with inconsistent silence intervals (2 to 7 min.). The mean number of notes produced per call series was 53 ± 23.7 and varied from 18 to 126 notes. The mean call series duration was 9.9 ± 4.5 s and varied from 3.3 to 23.1 s. A total of 499 notes and inter-note intervals (26 to 43) per male was measured. The mean note duration for the 14 males was 0.06 ± 0.01 s and varied from 0.02 to 0.09 s. The inter-note intervals within call series of the 14 males had a mean of 0.12 ± 0.02 s and a range of 0.07 to 0.26 s.

We noted large variation in the spectral parameters within individual calls and used the mean, maximum and minimum values to characterize the maximum, higher, and lower frequency traits for the 14 males. Because the spectral parameters were correlated [maximum and higher (r = 0.92), maximum and lower (r = 0.87), lower and higher (r = 0.65)], we present maximum frequency to illustrate individual variation in detail (Table 2). A sub-sample of thirty notes emitted in four series of calls was analyzed for each male. For the 14 males combined a total of 457 notes were measured, giving means for low, high and maximum frequency of 2.14 kHz (range 1.60–2.44 kHz), 2.37 kHz (range 2.02–2.82 kHz) and 2.26 kHz (range 1.89–2.55 kHz), respectively (Fig. 4).

Tadpoles description. The description is based on tadpoles at Gosner stage 36 (INPA-H 19552). Measurements of tadpoles in eight different developmental stages are presented in Table 3. The tadpoles are elongated (Fig. 5). The body is ellipsoid in dorsal view (Fig. 5 a) and flattened in lateral view (Fig. 5 b). Body and tail are 33% and 68 %, respectively, of total length; body wider than deep; snout bluntly rounded in dorsal view and in profile. Eyes located dorsally and directed dorsolaterally (Fig. 5 a and b). Nostrils oval located dorsally and directed dorsolaterally. Spiracle is single, sinistral, on the middle third of the body and below lateral midline (Fig 5 c, arrow); spiracular opening on the posterior third of the body and directed posteroventrally, not visible in dorsal view. Vent tube medial, attached to ventral fin, opening in line with the edge of the ventral fin. Caudal muscle is robust and higher than dorsal and ventral fins along the anterior third of tail. Dorsal-fin height is similar to ventral fin. The dorsal fin originates at the tail-body junction, and gradually increases for two-third of the tail length, and gradually diminishes after that to a rounded tip. The ventral fin originates at the posterior ventral terminus of the body, maintaining the same height throughout the proximal two thirds of the tail, and gradually diminishing to the tip (Fig. 5 a, b and c).

The oral disc (Fig. 5 d and e) is anteroventral, laterally emarginated with two rows of papillae only on lateral margins of disc. Papillae long, conical with convex extremities. Submarginal papillae absent. The anterior and posterior margins of the oral disc bare. Labial teeth dark, tooth row formula 2(2)/3; innermost upper row (A-2) interrupted medially. Lower tooth rows smaller than A-1; P-2 slightly longer than P-1 and P-3 is slightly smaller in length than P-1. Jaw sheaths darkly pigmented. Upper jaw sheath wide, arch-shaped; lower-jaw sheath wide, V-shaped, both sheaths finely serrated.

The colour in life is transparent to white. Due to the translucent skin, the coloration of the tadpoles in life reflects the background colour (Fig. 6 a and b). In preservative, the colour of body and tail are white to cream, skin and tail fins translucent; caudal musculature cream (Fig. 5 a, b and c). Chromatophores are scattered over the dorsal region of the body, dorsal surfaces of the forelimbs, proximal third of caudal musculature, and are scarce on the dorsal fin. The density of chromatophores diminishes gradually to lateral areas of the body and chromatophores are absent on the ventral surface of the body and ventral fin, which is transparent.

Natural history. Rhinella magnussoni occurs in sympatry with R. castaneotica, another member of the R. margaritifera species group (Caldwell & Araújo 2005). Males R. magnussoni call frequently during daylight hours from leaf-litter distant from streams or terrestrial pools. On 30 males heard between 18 and 27 February 2006, only one called at night. Most males called below fallen leaves. Oviposition sites were pools of water that formed on fallen tree trunks. They contained tadpoles of R. magnussoni in more than one developmental stage, indicating that clutches were deposited in the very same site at different times (Fig. 6 a and b). We found one site with tadpoles eating eggs (Fig. 6 a). Approximately 60 calling males were heard within a 2 km x 0.5 km area. Calling males were positioned 30–100 m apart and apparently exhibited site fidelity, returning to call at the same place after being caught and handled. Reproduction appears to be seasonal and occurs between January and March. At night, males and females were found resting on vegetation a 30 to 150 cm above ground.

Distribution. Rhinella magnussoni has been collected only from type locality, Belterra municipality, Pará state. However, it has also been seen and heard calling in the Floresta Nacional do Tapajos, at km 72 on the BR 163 highway, Belterra municipality (A. P. Lima, unpubl. data). Specimens were not collected from this locality because the collecting license did not include federal reserves.

Etymology. This species is dedicated to William E. Magnusson for his contributions to training the authors in herpetology in Amazonia.