Leptodactylus rhodomystax

Rodrigues, Domingos J., Menin, Marcelo & Lima, Albertina P., 2007, Redescription of the tadpole of Leptodactylus rhodomystax (Anura: Leptodactylidae) with natural history notes, Zootaxa 1509, pp. 61-67 : 62-64

Tadpoles of Leptodactylus rhodomystax

Description. The description is based on tadpole at stage 37 (INPA-H 15850). Body ovoid in lateral view ( Fig 1 A). Body length 15.7 mm; tail length 31.0 mm; body 50.6 % of tail length; total length 46.7 mm; body and tail 34 and 66 % of total length respectively. Body ovoid from above ( Fig 1 B). Width of body 10.0 mm. Body of greater width than height; height 6.3 mm. Body three times larger than tail muscle height. Maximum tail height two times larger than tail muscle height. Snout rounded in lateral and dorsal views. Eyes directed dorsolaterally. Interorbital distance 4.2 mm. Internarial distance 2.7 mm. Nostrils dorsolateral. Distance between eyes and nostrils 2.0 mm; distance between nostrils and mouth 2.3 mm. Spiracle single, sinistral, opening at mid-level of body; visible in dorsal view. Vent tube 2.1 mm along ventral midline, opening posteriorlly, with both walls attached directly to ventral fin.

Caudal muscle heavy, higher than dorsal and ventral fins along the anterior third of the tail. Dorsal fin originating at the tail-body junction, gradually increasing for one-third of the tail length, and gradually diminishing after that to tip. Ventral fin originating at the posterior ventral terminus of the body, slightly arched, and maintaining the same height throughout the proximal two-thirds of the tail, gradually diminishing to the tip.

Oral disc ( Fig. 1 C) anteroventral, 3.9 mm wide, 39.0 % of body width. Marginal papillae surround the oral disc, interrupted medially on anterior labium. Submarginal papillae present in posterior labium and on the lateral part of the anterior labium. Marginal and submarginal papillae of anterior labium greater than in posterior labium. Labial tooth row formula (LTRF) 2(2)/3. Gap of second anterior tooth row (A-2) 0.68 mm. All labial tooth rows nearly the same length. Upper jaw sheath wide, arch-shaped; lower jaw sheath wide, Vshaped; both finely serrated.

In life, color of body and tail black, belly bluish in individuals collected in the field. Color of body and tail of individuals maintained in laboratory is black or dark brown. Preserved, body color can vary from black to dark brown with a dark abdomen. Intestines not visible through skin. Caudal musculature dark brown to black; fins transparent pale black. Body shape of individuals collected in the field and maintained in the laboratory are similar to those collected directly from the field.

Measurements of tadpoles in other developmental stages are presented in Table 1 .

Snout-vent length of metamorphosed froglets was 18.0 mm (sd = 0.2 mm; n = 27). Froglets were similar to adults in color patterns and body shape ( Fig. 1 D).

Natural History. Ponds containing L. rhodomystax tadpoles had a mean size of 1.67± 0.47 m 2 (n = 21). We found two foam nests during our study period, both deposited between shrubs, roots, and fallen tree trunks near a pond (51 and 41 cm from pond edge). Tadpoles reach the pond after the flooding by rains. The clutches contained 290 and 247 eggs. Tadpoles were free-swimming, benthic, and found in the leaf litter of ponds between January and May. Tadpoles are intra-specific predators of tadpoles and inter-specific predators of eggs and tadpoles of Osteocephalus taurinus Steindachner, 1862 and tadpoles of Colostethus sp. On three occasions we observed tadpoles of L. rhodomystax aggregated and buried in dry soil.

Spatial and temporal distribution. In the first year of sampling (October 2002 to September 2003), we did not detect any L. rhodomystax tadpoles in ponds. In the second and third years of sampling we found L. rhodomystax tadpoles in 11 of the 31 sites sampled. It was present in eight of the 16 western watershed sites and three of the 15 eastern watershed sites. Leptodactylus rhodomystax occurred in nine sites in the second year of sampling and seven sites in the third year. Only five sites were occupied in both years ( Fig. 2 ).

Figures

FIGURE 1. Leptodactylus rhodomystax tadpole (INPA-H 15850) at stage 37, (A) lateral view, (B) dorsal view (scale = 10 mm), and (C) oral disc (scale = 1 mm). Froglet (D) (scale = 10 mm).

FIGURE 2. Mean number of L. rhodomystax tadpoles by site in relation to wet seasons sampled in RFAD, Amazonas, Brazil. Sites 1 – 8 = western watershed; sites 9 – 11 = eastern watershed.

Tables

TABLE 1. Mean measurements in mm (mean ± standard deviation) of 19 L. rhodomystax tadpoles in Gosner’s (1960) stages 25, 37, and 40.

Characteristics	Stage 25 (N=8)	Stage 37 (N=5)	Stage 40 (N=6)
Total length	24.26±0.50	50.66±1.21	53.28±0.26
Tail length	16.83±0.36	34.32±1.29	35.88±0.20
Maximum tail height	4.50±0.07	10.00±0.44	9.68±0.16
Tail muscle width	1.96±0.07	5.14±0.18	5.03±0.14
Body length	7.42±0.17	16.94±0.20	17.40±0.10
Tail muscle height	1.89±0.07	5.42±0.23	5.38±0.09
Internarial distance	1.55±0.05	2.94±0.07	2.75±0.12
Interorbital distance	1.68±0.08	4.32±0.12	5.00±0.07