Rhinella sebbeni, Vaz-Silva & Maciel & Bastos & Pombal, 2015

Vaz-Silva, Wilian, Maciel, Natan M., Bastos, Rogério P. & Pombal, José P., 2015, Revealing Two New Species of the Rhinella margaritifera Species Group (Anura, Bufonidae): An Enigmatic Taxonomic Group of Neotropical Toads, Herpetologica 71 (3), pp. 212-222 : 213-216

Rhinella sebbeni sp. nov.

( Figs. 1–2 )

Holotype. — MNRJ 53073 , adult male, Parque Ecológico Altamiro de Moura Pacheco (16 ° 34̍24̍̍S, 49 ° 10̍58̍̍W; 790 m above sea-level [asl]; in all cases, datum = WGS84), Goiânia municipality, State of Goiás, Brazil, collected on 11 November 2006 by R.P. Bastos.

Paratypes. — CHUNB 56423 and 56445, adult males, collected on 27 August 2004 , and CHUNB 57354 , adult female, collected on 17 October 2004 by A.K. Peres, Jr., same municipality of holotype . CEPB 4724 , adult male, 10 January 1997 ; CEPB 4711 , adult female, 9 December 1996 ; CEPB 4723 , adult female, 9 June 1997 ; CEPB 4725–4728 , adult females, 20 December 1996 ; CEPB 4731 , adult female, 2 December 1996 ; CEPB 4739 , adult female, 4 December 1996, Niquelândia municipality (14 ° 09̍S, 48 ° 22̍W; 690 m asl), State of Goiás, Brazil, collected by Systema Naturae Team during the Fauna Rescue of Hydroelectric Power Plant Serra da Mesa . CFBH 11591 , adult female, collected on 23 March 2006 by C.A. Brasileiro and M. Oyamaguchi ; CFBH 18652 , juvenile, collected on 28 January 2008 by T.G. Santos and K. Kopp, both in Fazenda Boa Vista , Ouro Verde de Goiás municipality (16 ° 13̍S, 49 ° 11̍W; 1040 m asl), State of Goiás, Brazil .

Diagnosis. —A species of the R. margaritifera group as defined by Pramuk (2006) based on the presence of an expanded posterior ramus of the pterygoid. Rhinella sebbeni sp. nov. is distinguished from other species by the following combination of features: (1) snout–vent length (SVL; range = 48.5–59.7 mm, in males; 54.7–66.7 mm, in females); (2) supraorbital and parietal crests evident; (3) supratympanic crest well-developed, wider than bony protrusion at the angle of jaws in dorsal view; (4) presence of dorsolateral line tubercles; (5) tympanum evident; (6) snout nearly acute in lateral view and mucronate in dorsal view; (7) presence of bony protrusion at the angle of jaws; (8) presence of rostral keel at the tip of snout; (9) dorsal skin with a small concentration of granules, more concentrated on the flanks; (10) absence of vertebral apophyses; (11) foot webbing poorly developed; and (12) parotoid gland well-delimited, with small and elliptical shape presenting a lateral line of tubercles.

Comparisons with other species. — Rhinella sebbeni sp. nov. differs from R. margaritifera by well-developed cephalic crests (vs. hypertrophied cephalic crests), absence of vertebral apophyses (vs. presence), and an evident bony protrusion at the angle of jaws (vs. bony protrusion slightly evident; see Lavilla et al. 2013). From R. acutirostris and R. alata , this new species differs by the presence of rostral keel at the tip of snout, cephalic crests well-developed, a bony protrusion at the angle of jaws, and larger size of males 48.5– 59.7 mm (vs. absence or poorly bony protrusion at the angle of jaws, cephalic crest poorly developed, and males with 35.3 mm in R. acutirostris and 36.8 mm in R. alata ; see Thominot 1884; Lötters and Köhler 2000; Santos et al., 2015). Further, from R. acutirostris by the well-developed cephalic crests (vs. poorly developed) and larger size of males 48.5–59.7 mm (vs. 35.3 mm; see Lötters and Köhler 2000). Rhinella sebbeni sp. nov. can be distinguished from R. proboscidea by the presence of an evident continuous line of tubercles along the lateral side body, including the posterior border of the parotoid gland (vs. less evident), cephalic crests welldeveloped (poorly developed in R. proboscidea ), snout lacking a developed proboscis (vs. developed proboscis), nearly acute snout in lateral view (vs. pointed), skin on dorsum slightly granulose (vs. smooth), and parotoid gland well-delimited (vs. indistinct). From R. roqueana , this new species is distinguished by having an evident tympanum (vs. barely distinct), snout in lateral view nearly acute (vs. snout nearly vertical), snout mucronate in dorsal view (vs. truncated), absence of vertebral apophyses (vs. presence), parietal crest poorly developed (vs. well-developed), and smaller size in males 48.5–59.7 mm (vs. SVL 70.0–79.0 mm; Melin 1941). Rhinella sebbeni sp. nov. is distinguished from R. dapsilis by the posterior border of the parotoid gland having a line of tubercles that are continuous along the lateral side of body (vs. absence), presence of lateral line of tubercles on parotoid gland (vs. absence), snout lacking a developed proboscis (vs. developed proboscis), postorbital crest well-developed (vs. poorly developed), skin on dorsum slightly granulose (vs. smooth), and bony protrusion welldeveloped at the angle of the jaws (vs. poorly developed; Myers and Carvalho 1945). From R. castaneotica , R. sebbeni sp. nov. differs in having a well-developed supratympanic crest (vs. poorly developed), larger size of males 48.5– 59.7 mm (vs. 30.9–36.8 mm), well-developed postorbital crest (vs. poorly developed), presence of lateral line of tubercles on parotoid gland (vs. absence), tympanum evident (vs. not evident), and skin on dorsum slightly granulose (vs. smooth; see Caldwell 1991). This new species differs from R. stanlaii by having a poorly developed supraorbital crest (vs. hypertrophied), postorbital crest well-developed (vs. poorly developed), snout in lateral view nearly acute (vs. protruding), and presence of vocal slits (vs. absence; Lötters and Köhler 2000). From R. sclerocephala , R. sebbeni sp. nov. differs by the absence of vertebral apophyses (vs. presence), snout mucronate in dorsal view (vs. truncated), and foot webbing poorly developed (vs. developed; see MijaresUrrutia and Arends 2001). From R. scitula , this new species is distinguished by well-developed cephalic crests (poorly developed), bony protrusion at the angle of jaws poorly developed (vs. well-developed), skin on dorsum slightly granulose (vs. extremely granulose), presence of lateral line of tubercles on parotoid gland (vs. absence), small and elliptical parotoid gland (vs. globose), and larger size of males 48.5–59.7 mm (vs. 33.8–46.1 mm; see Caramaschi and Niemeyer 2003).

From R. hoogmoedi , this new species is distinguished by its slightly granulose dorsal skin (vs. rugose), rostral keel at the tip of snout (vs. absence), and larger parotoid gland ( Caramaschi and Pombal 2006). This new species is distinguished from R. paraguaŋensis by the well-developed cephalic crests (vs. poorly developed), snout nearly acute in lateral view (vs. rounded), rostral keel at the tip of snout poorly developed (developed) and skin on dorsum slightly granulose (vs. very granulose; Ávila et al. 2010). From R. lescurei , this new species is distinguished by its snout nearly acute in lateral view (vs. pointed), by the well-developed postorbital crest (vs. poorly developed), larger size of males 48.5–59.7 mm (vs. 30.2–38.9 mm), and vestigial webbing in toes (vs. developed; Fouquet et al. 2007a). From Rhinella magnussoni , R. sebbeni sp. nov. can be distinguished by the well-developed supratympanic crest (vs. poorly developed), larger size of males 48.5–59.7 mm (vs. 36.0– 45.3 mm), snout nearly acute in lateral view (vs. pointed), snout mucronate in dorsal view (vs. pointed), and skin on dorsum slightly granulose (vs. rugose; Lima et al. 2007). From R. martŋi , this new species differs in the absence of vertebral apophyses (vs. presence), snout in lateral view nearly acute (vs. slightly rounded), vestigial webbing in toes (vs. developed; see Fouquet et al. 2007a). This new species is distinguished from R. ocellata by its well-developed cranial crests (vs. undeveloped), tubercles on dorsal skin poorly developed (vs. developed), snout mucronate in dorsal view and nearly acute in lateral view (vs. rounded in dorsal and lateral views), rostral keel at the tip of snout (vs. absent), dorsal cream uniform sometimes presenting small spots (vs. dorsal ocelli color pattern; see Leão and Cochran 1952; Caldwell and Shepard 1997), bony protrusion at the angle of jaws poorly developed (vs. well-developed). Rhinella sebbeni sp. nov. is distinguished from R. ŋunga by its snout being mucronate in dorsal view (vs. slightly pointed), tympanic membrane and tympanic annulus present (vs. absent), bony protrusion at the angle of jaws poorly developed (vs. undeveloped), vestigial webbing in toes (vs. developed), and by its cephalic crests being well-developed (vs. poorly developed; Moravec et al. 2014).

Rhinella sebbeni sp. nov. differs from R. cristinae by the evident tympanum (vs. absent), larger size of males 48.5– 59.7 mm (vs. 30.7–34.3 mm, n = 9), and the bony protrusion at the angle of jaws poorly developed (vs. bony protrusion undeveloped; Veléz-Rodriguez and Ruiz-Carranza 2002). From R. iserni , this new species differs in the absence of vertebral apophyses (vs. presence), and tympanum evident (vs. absent; Jimenez-de-la-Espada 1875; Caramaschi and Pombal 2006). From R. ceratophrŋs , this new species differs in the absence of triangular projecting dermal flaps on the eyelids and at the corners of mouth (vs. presence; Fenolio et al. 2012).

Description of the holotype. —Body robust; head wider than long, head length 70.8% of head width; head length 29.5% of SVL; head width 41.6% of SVL. Snout mucronate in dorsal view, with a rostral keel at the tip of snout; nearly acute in lateral view. Tip of snout and head slightly concave; canthus rostralis well-defined by canthal crests, curved; loreal region slightly concave. Nostrils slightly protuberant, slightly directed dorsolaterally, nearer to the tip of snout than to eyes; internarial distance shorter than the eye–nostril distance, eye diameter, upper eyelid width, and tympanum diameter; eye–nostril distance longer than the eye diameter, tympanum diameter, and upper eyelid width; eye diameter slightly longer than the upper eyelid width and tympanum diameter; upper eyelid width 48.8% of interorbital distance. Canthal and supraorbital crests developed, parietal poorly developed and absence of preorbital crest; well-developed supratympanic crest, forming conspicuous lateral ledges; distance of the extremities of the supratympanic crests nearly larger than head width. Tympanum large, with a distinct annulus only anteriorly; vertical tympanum diameter nearly equal to the diameter of the eye. Parotoid glands, in dorsal view, small, triangular; in lateral view, elliptical, continuous to the supratympanic crest; parotoid gland length larger than the supraorbital crest length. External border of the parotoid gland with a line of pointed tubercles, which continues along the lateral side of body to the groin. Absence of salient apophyses on dorsum. Lips with small numerous tubercles; eyes visible from below. A nearly V-shaped incision in the maxilar symphysis; presence of a bony protrusion at the angle of jaws. Vocal sac not expanded externally and vocal slits present. Choanae small, ovoid, lateral, widely separated; medium tongue size, longer than wide, free and not notched posteriorly.

Forelimbs robust, forearms slightly more robust than the arms. Hand with medium-sized fingers; slender fingers with reduced webbing only at the base of fingers; fingers in ascending order of size, IV <II <I <III; lateral fingers with a line of spinulose tubercles. Finger tips not expanded, smooth, posteriorly delimited on the dorsal and ventral faces by a groove. Palmar tubercle large, rounded, smooth; thenar tubercle small, approximately one fourth of the palmar tubercle, nearly rounded, smooth. Subarticular tubercles developed, conical, unique. Many supernumerary tubercles of varied sizes, distinct, conical, irregularly distributed on the ventral surfaces of hand and fingers. A few scattered black spinules on the inner dorsal surface of Finger I.

Hindlimbs short, robust. Tibia length slightly shorter than thigh length; tibia length 95.5% of thigh length and 42.8% of the SVL; thigh length 44.8% of SVL; sum of tibia and thigh lengths 87.0% of the SVL; tarsus-foot length larger than the tibia and thigh lengths, 58.9% of the SVL. Foot with short toes, moderately robust, in ascending order of size, I <II <V = III <IV; toes webbing poorly developed; external surfaces of the first, fifth, and free part of the third toes with a line of spinulose tubercles; webbing formula I1 – 2II1 – 2 1/2 III1 1/2 – 4IV4 – 1 1/2 V. Tips of toes slightly expanded, smooth. Outer metatarsal tubercle small, rounded, protruding; inner metatarsal tubercle large, approximately three times the outer, ovoid, with the distal border free. Subarticular tubercles small, conical, unique. Many supernumerary tubercles distinct, conical, unequal in size, approximately aligned on the ventral surfaces of foot and toes.

Skin on dorsum, flanks, and limbs granulose, with many small tubercles, rounded, irregularly distributed without forming a defined pattern; dorsal region poorly granulose. Ventral surfaces finely granulose.

Measurements of the holotype (in mm). —Snout–vent length 55.9; head length 16.5; head width 23.3; internarial distance 3.0; eye–nostril distance 5.3; eye diameter 4.7; upper eyelid width 4.3; interorbital distance 8.8; postorbital crest length 9.0; horizontal tympanum diameter 3.6; vertical tympanum diameter 4.8; parotoid gland length 9.9; hand length 16.1; thigh length 24.7; tibia length 23.6; foot length (tarsus + foot) 32.7.

Color of the holotype in preservative. —Dorsum and laterals of body and limbs uniformly brown; a grayish brown bar on forearm, tibia, and tarsus; ventral surfaces of feet and tarsus gray with brown tubercles. A whitish thin dorsal line from head to the posterior third of the body.

Variation and color in life. —Variations in measurements are summarized in Table 1 . In life, dorsum uniformly brown or presenting small spots ( Fig. 3 ). Sometimes, presence of a dark stripe on dorsal forearm and slight vertebral line ( Fig. 4 ). CFBH 18652 is brownish with light spots throughout the body, especially on the limbs. In preservative, its dorsum is cream or brown. Specimens CEPB 4721, 4724–4726, and CEPB4 728 present dark spots on dorsum and the other specimens in type-series present uniform coloration. Blotch on frontoparietal region poorly marked in the specimen CEPB 4726. Ventral pattern well reticulated in specimen CHUNB 56445. Specimen CEPB 4711 presents malformation of left toes and CEPB 4731 and its third finger of the right hand is shorter than the left hand.

Etymology. —The specific name is a tribute to our friend and colleague Antonio Sebben (Universidade de Brasília) a notable morphologist, physiologist, and photographer, for his contribution to the knowledge of the Brazilian herpetofauna.

Natural history. —Adults or subadults of R. sebbeni sp. nov. can be found inside pristine forest (Ciliar and Dry Seasonal forests), in the leaf litter. On one occasion, males were observed vocalizing in ponds at the edges of a forest. In a survey conducted by RPB and C. Alves in the area flooded by the reservoir of the João Leite River, R. sebbeni sp. nov. was collected in pitfall traps in the rainy season (November– March) in periods from 2006 to 2010. A female (CEPB 4723) had 2,225 brown and cream ovarian eggs, with an average diameter of 1.73 ± 0.19 mm (n = 10; range = 1.34–1.99 mm). Rhinella sebbeni sp. nov. was sympatric and more abundant in areas where it occurs than Rhinella schneideri ( Werner 1894) , a species common in open areas. We captured 18 specimens of R. sebbeni sp. nov. in each rainy season between 2006 and 2010, compared to only four individuals of R. schneideri .

Geographic distribution. — Rhinella sebbeni sp. nov. has been found in Goiânia (type locality), Ouro Verde de Goiás, and Niquelândia municipalities, in the State of Goiás, Central Brazil ( Fig. 5 ). These localities are located within Cerrado biome. This biome covers approximately 2 million km 2, representing 22% of Brazil ̕s land area (extending from the southern borders of the Amazonian forest to areas in the southern States of São Paulo and Paraná), plus small areas in eastern Bolivia and northwestern Paraguay. The distribution of Cerrado is coincident with the plateau of central Brazil ( Oliveira-Filho and Ratter 2002).

Figures

FIG. 1.—Dorsal and ventral views of the holotype of Rhinella sebbeni sp. nov. (MNRJ 53073; snout–vent length = 55.9 mm).

FIG. 2.—Holotype of Rhinella sebbeni sp. nov. (MNRJ 53073). Dorsal (A) and lateral (B) views of head (scale bar = 10 mm) and palmar (C) and plantar views (D). Scale bar = 5 mm.

FIG. 3.—Rhinella sebbeni sp. nov., (A) adult in life from type-locality (uncollected specimen; photograph by D.M. Silva), and (B) a juvenile specimen (CFBH 18652) from Ouro Verde de Goiás, Goiás state, Brazil (photograph by K. Kopp).

FIG. 4.—Variation in dorsal (A) and ventral (B) color pattern of Rhinella sebbeni sp. nov. (type series).

FIG. 5.—Geographic distribution of Rhinella sebbeni sp. nov. (circles), showing Goiânia Municipality (type locality; star), and Rhinella gildae sp. nov., São Pedro da Água Branca (type locality; square). GO = State of Goiás; DF = Federal District; TO = State of Tocantins; MS = State of Mato Grosso do Sul; MT = State of Mato Grosso; BA = State of Bahia; MA = State of Maranhão; PI = State of Piauí; MG = State of Minas Gerais; SP = State of São Paulo; PR = State of Paraná.