Rhinella proboscidea (Spix, 1824)

Menin, Marcelo, Rodrigues, Domingos J. & Lima, Albertina P., 2006, The tadpole of Rhinella proboscidea (Anura: Bufonidae) with notes on adult reproductive behavior, Zootaxa 1258, pp. 47-56 : 49-52

Tadpoles of Rhinella proboscidea (Spix, 1824)

Measurements in mm: Mean ± standard deviation (range) of five specimens (INPA­H 15841) in developmental stage 37 according to Gosner (1960): total length 17.88±0.44 (17.20–18.30); body length 6.28±0.13 (6.20–6.50); maximum body height 3.06±0.48 (2.20–3.30); maximum body width 4.32±0.32 (3.80–4.60); tail length 11.60±0.48 (11.00–12.10); maximum tail height 3.00±0.27 (2.60–3.30); tail muscle height 1.14±0.05 (1.10–1.20); tail muscle width 1.06±0.05 (1.00–1.10); height of dorsal fin 0.92±0.04 (0.90–1.00); height of ventral fin 0.94±0.09 (0.80–1.00); maximum eye diameter 0.92±0.05 (0.83–0.97); maximum nostril aperture diameter 0.30±0.03 (0.27–0.33); interorbital distance 0.90±0.07 (0.80–1.00); internarial distance 0.72±0.04 (0.70–0.80); eye­nostril distance 0.34±0.05 (0.30–0.40); nostril­snout distance 0.84±0.09 (0.80–1.00); vent tube length 0.66±0.21 (0.30–0.90); width of oral disc 1.82±0.12 (1.73–2.00). Measurements of tadpoles in other developmental stages are presented in Table 1 .

Description. The description is based on a tadpole at stage 37 ( Gosner 1960) raised in the laboratory. Body is depressed in lateral view ( Fig. 1 A, stage 37) and oval in dorsal view ( Fig. 1 B). Body and tail 35 % and 65 % of total length respectively. Body wider than deep. Snout bluntly rounded in dorsal view and rounded in profile. Eyes located dorsally and directed dorsolaterally. Nostrils oval located dorsally and directed dorsolaterally. Internarial distance larger than eye­nostril distance; maximum nostril diameter similar to eye­nostril distance. Interorbital distance is similar to maximum eye diameter. Spiracle single, sinistral, on the middle third of the body and below lateral midline; spiracular opening on the posterior third of the body and directed posteroventrally, visible in dorsal view. In one of 121 individuals examined the spiracle was dextral. Vent tube positioned along ventral midline, attached to ventral fin.

Caudal muscle heavy, higher than dorsal and ventral fins along the anterior third of the tail. Dorsal fin height similar to ventral fin. The dorsal fin originates at the tail­body junction, and quickly increases for one­third of the tail length, and gradually diminishes after that to a bluntly rounded tip. The ventral fin originates at the posterior ventral terminus of the body and is slightly arched, maintaining the same height throughout the proximal two­thirds of the tail, and gradually diminishing to the tip.

The oral disc ( Fig. 1 C) is anteroventral, laterally emarginated with a single row of papillae only on lateral margins of disc. Papillae long, conical with convex extremity; 6­7 papillae on anterior labium and 4­5 on posterior labium. The anterior and posterior margins of the oral disc bare. Submarginal papillae absent. Labial teeth dark, tooth row formula 2(2)/3; innermost upper row (A­2) interrupted medially by a gap of 0.33± 0.11 mm (0.20–0.50). Labial teeth on posterior labium decrease in size from P­1 to P­3, labial teeth on P­3 very tiny. Lower tooth rows slightly smaller than A­1; P­2 slightly longer than P­1 and P­3 is subequal in length to P­2. Jaw sheaths dark pigmented. Upper jaw sheath wide, arch­shaped; lower jaw sheath wide, V­shaped, both finely serrated ( Fig. 1 C).

In life, the color of body and tail light brown, skin and tail fins translucent; caudal musculature light brown; fin opaque; color is similar in preservative. Cromatophorus are distributed in dorsal region of the body, dorsal surfaces of the forelimbs, caudal musculature, and are scarce on dorsal fin. The cromatophorus diminish gradually to lateral areas of the body and are absent on the ventral surface of the body and ventral fin, which is transparent. The color pattern and body shape of individuals collected in the field and maintained in the laboratory are similar to those collected directly from the field.

Metamorphosed froglets measured 6.00 ± 0.58 mm (5.50–7.00; n = 5). The froglets were brown and had the body shape similar to adults.

Adult reproductive behavior. Three groups were found reproducing in May (100 individuals in 2001, 10 individuals in 2003, 50 individuals in 2005). Two groups were found in April (40 and 50 individuals in 2004). However, vocalizations were also heard in March, April and May 2004. Males called during the night and during the day for two days (groups with 10 and 40 males) and three days (groups with 50 and 100 males). Choruses of males, clutches, and tadpoles were observed in temporary pools near streams. Temporary pool areas varied between two and five m2. Tadpoles were also observed in the water of temporary streams and headwaters of streams. On two occasions, five and nine females were found dead on the bottom of temporary pools. Three dead females were clasped by males.

Male R. proboscidea did not call from fixed positions. Males frequently moved toward any toad that approached to within a few centimeters. Males struggled among themselves for possession of females, with one or more (up to five) unpaired males attempting to displace a male in amplexus.

The clutches were bead­like gelatinous strings, with eggs disposed uniserially. We collected two clutches from the field, containing 439 and 473 eggs. Mean egg diameter of these clutches was 2.76 mm (sd = 0.43; n = 10 eggs; range = 2.4–3.4). Eggs were black in the animal pole and cream in the vegetal pole.

We collected three clutches in plastic bags on 10 May 2003 and maintained them in the laboratory. The first metamorphosed individuals emerged about 25 days after the deposition of clutches. Time to reach metamorphosis in the field was about 20 days.

Figures

FIGURE 1. Rhinella proboscidea tadpole at stage 37 (Gosner, 1960), (A) Lateral view, (B) Dorsal view (scale = 5 mm), (C) Oral disc (scale = 1 mm).

Tables

TABLE 1. Mean measurements in mm (± standard deviation) of 20 tadpoles of R. proboscidea in Gosner’s (1960) stages 34, 36, 38, and 41.

Characteristics Stage 34	Stage 36	Stage 38	Stage 41
(N=5)	(N=5)	(N=5)	(N=5)
Total length 16.44±0.78	17.36±1.01	17.76±1.19	17.16±1.20
Body length 6.04±0.38	6.36±0.24	6.24±0.45	6.02±0.28
Tail length 10.40±0.50	11.00±0.82	11.52±0.78	11.34±0.91
Maximum tail height 2.72±0.15	3.12±0.31	2.90±0.37	2.72±0.28
Tail muscle height 1.14±0.09	1.20±0.07	1.14±0.09	1.16±0.05
Tail muscle width 1.02±0.13	1.08±0.08	1.06±0.09	1.04±0.05
Internarial distance 0.72±0.04	0.74±0.05	0.76±0.05	0.74±0.05
Interorbital distance 0.84±0.05	0.90±0.00	0.88±0.08	0.86±0.05