Leptodactylus pustulatus, Peters, 1870

De Sá, Rafael O., Brandão, Reuber & Guimarães, Lorena Dall’Ara, 2007, Description of the tadpole of Leptodactylus pustulatus Peters, 1870 (Anura: Leptodactylidae), Zootaxa 1523 (1), pp. 49-58 : 50-55

Tadpoles of

Leptodactylus pustulatus

are exotrophic, lentic, and benthic guild members (McDiarmid & Altig 1999, guild IIA1). Tadpoles have an oval, elongated, and compressed body, without visible constriction ( Fig. 1 ). Body length represents 37.2% of total length, whereas body width is about 1.3X of body height. The maximum body width is located at the level of the eyes. The snout is rounded in lateral and dorsal view. The eyes are small, rounded, and dorsolaterally positioned, and are visible in dorsal and lateral view. The external nares are about half way between the eyes and the tip of the snout; narial openings are laterodorsal, small, rounded, and show margins marked by lighter coloration, but without a marginal rim. The orbitonasal line is not visible. The lateral line system is distinctly visible as light dots that run caudally from the tip of the snout, pass dorsal to the nares and eyes, run ventrally behind the eye and posteriorly over the dorsal body, and extend into the anterior half of the caudal musculature; lateral line system is also visible in the area above and in front of the spiracle. Tail fins are low; dorsal and ventral fins are about equal in height and nearly parallel to the tail musculature. The dorsal fin originates at the tail and body junction; the ventral fin originates at the posterior ventral terminus of the body and it is hidden by the vent tube. Maximum tail height is about 17% higher than body height, the tail fins slope uniformly and gradually to a rounded tail tip. The main tail axis is eutiurial; the myotomes of the tail musculature are poorly defined, almost indistinguishable in the tail posterior half, and extend to the tip of the tail. The spiracle tube is sinistral, simple, short, and posterolaterally directed; spiracular opening is midlateral and slightly elliptical. The vent tube and vent tube’s opening are medial relative to the ventral fin; vent tube opening is circular.

The oral disc is not emarginate and anteroventrally positioned; it corresponds to about 30.8% of the body width ( Fig. 2 ). A double row of large and rounded marginal papillae are found on the ventral and lateroventral margins of the oral disc, whereas the laterodorsal margins bear a single row of marginal papillae; a large rostral gap occupies most of the upper labium (about 54% of the width of the oral disk); mental gap is absent. No submarginal or intramarginal papillae were found. The labial tooth row formula is 2(2)/3; all labial tooth rows are sub-equal in length; tooth row A-2 is interrupted by a wide gap (about 24% of the length of A-1). Upper and lower jaw sheaths are wide, pigmented in no more than 1/4 of their width, and their edge is serrated.

Coloration of larvae. In life, the larvae of Leptodactylus pustulatus are overall dark brown, with darker tails. Specimens in 10% formalin are overall black, lighter on the ventral surfaces of body, with intestinal coils slightly visible through the ventrolateral skin of the body. The dorsal and dorsolateral surfaces of the body are homogeneously black, grading continuously to a dark gray on the ventral surfaces. The tail fins and tail musculature are smooth dark gray.

Measurements of larvae (in mm, n = 4). Total length x = 29.07 ± 0.91; body length x = 10.79 ± 0.34; body height x = 4.54 ± 0.30; body width x = 5.82 ± 0.25; tail height x =5.98 ± 0.13; tail length x = 18.28 ± 0.84; eye diameter x = 1.32 ± 0.04; eye-nostril distance x = 1.23 ± 0.13; interorbital distance x = 2.35 ± 0.13; internarial distance x = 1.62 ± 0.09; width of oral disc x = 1.99 ± 0.04; body length/total length x = 36.12%; eye diameter/body length x = 12.23%.

Internal Oral Anatomy (Stage 36).

Buccal roof. The oral roof is overall longer than wide, with a relatively narrow prenarial arena. A broad (width about 25% greater than its height) rectangular ridge with few pustulations is present in the prenarial arena. Two pairs of large, long, pustulated postnarial papillae are found at the anterior tip of the internal nares. The most anterior pair is almost twice the length of the second pair. Internal nares are narrow, elliptical slits positioned in a 45° angle relative to the main axis of the buccal roof; nares are found posteriorly, in the anterior third of the buccal roof ( Fig. 3 ). Narial walls are thick and the posterior margin of each nare bears papillae, whereas the anterior edge appears smooth; no narial valve was observed. Lateral ridge papillae are absent. A few pustulations are found on the postnarial arena between the internal nares and the median ridge; a pair of simple and short papillae is found immediately in front of the median ridge. The median ridge is overall triangular and has an irregular edge; the height of the median ridge is less than half of its width. Buccal roof arena (BRA) rounded, bounded anteriorly by the median ridge, laterally by numerous elongated and pointed papillae that are mostly arranged in a double row, and posteriorly by a single row of papillae that are slightly shorter than the lateral ones. BRA field densely and evenly scattered with pustulations. Dorsal velum long, curving gradually towards the midline; margin of velum bears papillae. The glandular zone of the velum is wide.

Buccal floor overall triangular and broad ( Fig. 4 ). One pair of infralabial papillae present. The tongue anlage has a large lingual papilla with irregular margins. Buccal floor arena (BFA) is semicircular and defined by several pairs of long and conical papillae; BFA homogenously scattered with pustulations. Velar surface free; posterior margin jagged by marginal projections; median notch distinct and secretory pits present. Gill filters of moderate size with an average filter mesh.

Chondrocranial Anatomy (Stage 35).

The chondrocranium of Leptodactylus pustulatus is about 10% longer than wide ( Fig. 5 ). The suprarostral consist of thin corpora ventrally fused at the midline, forming a wide U-shaped space between them. The corpora are continuous dorsolaterally with the suprarostral alae. The cornua trabeculae are narrow and long, their length represents about 24% of the total chondrocranial length and they diverge in a V-shape fashion. The processus (p.) lateralis trabeculae of the cornua trabeculae is indistinct, whereas the p. quadratoethmoidalis of the commissura quadratocranialis anterior is long and distinctly visible. At stage 35, the basicranial fenestra is closed; two pairs of foramina, f. craniopalatina and f. carotica primaria, are clearly visible. The orbital cartilages are well developed and confluent with the otic capsules, forming the lateral wall of the braincase, where the foramen opticum, oculomotorium, and prooticum are visible. Dorsally, the frontoparietal fenestra remains undivided. The otic capsules are ovoid and their length is about 34% of the total chondrocranial length; they possess a narrow crista parotica that bears a distinct, pointed, and overall triangular-shaped p. anterolateralis; no p. posterolateralis was found. Anteriorly, the palatoquadrate connects to the braincase via the commissura quadratocranialis anterior; a p. pseudopterygoideus is absent; posteriorly, the connection to the braincase is through the p. ascendens, with a low attachment. The posterior curvature of the palatoquadrate extends beyond the level of the attachment of the p. ascendens to the braincase. The p. muscularis quadrati is broad and its rounded tip connects to the commissura quadratocranialis anterior by a chondrified commissura quadratoorbitalis. The pars articularis quadrati is broad and short and articulates with a robust and sigmoidshaped Meckel’s cartilage. The infrarostrals connect, but are not fused, ventromedially forming a V-shaped structure. The ceratohyalia of the visceral skeleton are wide and bear two short and pointed processes, the p. anterolateralis and p. anterior hyalis ( Fig. 6 ). The ceratohyalia are connected by a distinct pars reuniens that is continuous with the copula posterior that bears a short and rounded p. urobranchialis. The hypobranchial plates are not fused. The hypobranchial plates possess a distinct, hook-like, p. anterior branchialis. The branchial baskets consist of four well-developed ceratobranchials; ceratobranchials I and IV are broadly continuous with the hypobranchial plates. Ceratobranchials II and III have a closed p. branchialis.

Natural history. The habitat where Leptodactylus pustulatus was found corresponds to “veredas” environments, i.e., flooded grasslands and areas of flooded gallery forests (see Ribeiro & Walter 2001 for an account of Cerrado physiognomies). Calling males were more commonly found in lentic habitats, usually large ponds with deeper areas of between 1 and 2 m. Individuals were observed calling close to aquatic plants and dead trunks, sometimes at the deeper areas of the ponds. The most common vegetation in these ponds was “buriti” palms ( Mauritia vinifera ), Cyperaceae , and Poaceae at the edges, and Nymphaceae, Araceae , Musaceae , and Pontederiaceae vegetation covered the deeper areas. Leptodactylus pustulatus has also been found in small cattle dams and other types of flooded areas ( Brandão & Heyer 2005).

Tadpoles collected on October 15, 1995, were found on a pond formed by the damming of a stream by road shaft. The larvae were swimming around a female Leptodactylus pustulatus while this was floating on the water surface. When disturbed, the tadpoles congregated above the female and remained still, the female did not show any defensive or aggressive behavior while the tadpoles were collected. The tadpoles exhibited schooling behavior by forming a massive cluster of tadpoles that swam around the female. Recently metamorphosed L. pustulatus were caught in pitfall traps in an area of seasonal flooded Cerrado at Palmas, Tocantins State, during the months of November and December 1995. Adults were always found in aquatic environments. The water snake, Helicops angulatus , and the wolf fish, Hoplias sp. , were observed in same habitat of L. pustulatus . These species are likely predators of both Leptodactylus tadpoles and adults individuals. Other anurans found along with L. pustulatus at Palmas and Britânia were Leptodactylus podicipinus, Pseudis tocantins, Lysapsus caraya, Hypsiboas punctatus , and Hypsiboas raniceps .

Tadpoles were also collected on December 21, 2004, at 21:00 hs, at Matrinchã, west Goiás State. A female Leptodactylus pustulatus was observed attending a group of about 50 tadpoles in a small pond in “vereda” habitat surrounded by cattle pastures; the pond had a sandy substrate and the tadpoles were on the shallow margin of the pond (about 4–5 cm deep). The larvae were swimming around a female L. pustulatus that floated on the surface of the pond. During the 1.5 hour of observation, the female grouped and displaced the tadpoles that surrounded her three times; we cannot discard that this behavior may have been triggered by our presence in the pond. The grouping and moving of the larvae to other areas on the edge of the pond was accomplished through movements of the anterior and posterior limbs; these movements appear to the human eye as if the female was “grouping” the larvae. The female had an overall triangular area on the dorsal surface of the head that lacked skin. This injury could be caused by territorial combats or predator attacks, but we did not directly observed this.

Figures

FIGURE 1. Tadpole of Leptodactylus pustulatus, Gosner stage 39, CHUNB 49619. Bar = 5 mm.

FIGURE 2. Oral disk of Leptodactylus pustulatus, Gosner stage 39, CHUNB 49619. Bar = 1 mm.

FIGURE 3. Buccal roof anatomy of Leptodactylus pustulatus, Gosner stage 36.

FIGURE 4. Buccal floor anatomy of Leptodactylus pustulatus, Gosner stage 36.

FIGURE 5. Dorsal view of the chondrocranium of Leptodactylus pustulatus, Gosner stage 35, CHUNB 38511. Bar = 1mm

FIGURE 6. Ventral view of the hyobranquial apparatus of Leptodactylus pustulatus, Gosner stage 35, CHUNB 38511. Bar = 1mm.