Pleurodema bibroni Tschudi

Kolenc, Francisco, Borteiro, Claudio, Baldo, Diego & Ferraro, Daiana P., 2009, The tadpoles and advertisement calls of Pleurodema bibroni Tschudi and Pleurodema kriegi (Müller), with notes on their geographic distribution and conservation status (Amphibia, Anura, Leiuperidae), Zootaxa 1969, pp. 1-35 : 5-8

Pleurodema bibroni Tschudi

( Fig. 2 A, 2B)

At stages 33–36 mean total length is 35.4 ± 3.1 mm, the body is globose, slightly depressed (mean BMH/ BMW = 0.94 ± 0.05). The body length is about 40% of total length (mean BL/TL = 0.42 ± 0.05), body shape is oval in dorsal view with a constriction behind the cephalic region, and the maximum width is placed at the posterior portion of the head or sometimes at the abdominal region. The ventral contour is slightly convex in lateral view; the dorsal contour slopes from the anterior edge of the oral disc to the posterior border of the eyes, and straight from the eyes to the origin of the dorsal fin. The snout is rounded in dorsal view and truncated in lateral view. The nostrils are rounded and placed in a depression; they are dorsolaterally positioned (mean EN/BWN = 0.38 ± 0.04), slightly closer to the eyes than to the tip of snout (mean FN/ END = 1.12 ± 0.15) and more visible dorsally than laterally. Their openings are directed dorsally and slightly to the front and present a slightly elevated marginal fleshy rim. The eyes are small (mean E/BWE = 0.18 ± 0.02), dorsally located (mean IOD/BWE = 0.61 ± 0.04), dorsolaterally oriented, and not visible in ventral view. The pineal end organ is visible as a less pigmented spot between the anterior edges of the eyes. The spiracle is single, lateral, sinistral, short, posterodorsally directed, and placed in the second third of the body (mean RSD/BL = 0.58 ± 0.06). The spiracle inner wall is fused to body wall except for the very distal end which folds to delimit the spiracle opening. Spiracle opening is oval, placed below body midline, being its diameter smaller than the tube diameter; it is visible laterally and sometimes also ventrally. The intestinal ansa was observed displaced to the left behind the spiracle opening in most specimens, or approximately at the center of the abdominal ventral surface in the others. The vent tube is medial; it starts at midline but opens to the left in 70% of the examined specimens or to the right in the others, due to a variable folding of the ventral fin at its origin. A medium sized saccular structure underlies the limb buds and encloses the vent tube. The tail is medium-sized (mean TAL/TL = 0.58 ± 0.05), and both fins are as high as the body height (mean MTH/BMH = 0.99 ± 0.10). The dorsal fin originates on the body-tail junction and its free margin is regularly curved, convex, with the maximum height at the middle length of the tail. It is slightly higher than the ventral fin (mean DFH/VFH = 1.1 ± 0.1). Ventral fin originates from the saccular structure and presents a smoothly convex free margin. The tail axis is straight, and the tail smoothly stretches towards the tip in it last half, ending bluntly rounded. The tail musculature does not reach the end of the tail, and myomeres are more visible in the proximal half. Neuromasts are very small and hardly visible, even with the help of magnification and after staining the tegument with methylene blue. The oral disc ( Fig. 3 A) is anteroventral, medium sized (mean OD/BMW = 0.43 ± 0.01), laterally emarginated, and has a large dorsal gap (DG/OD = 0.63 ± 0.04). Marginal papillae are arranged in a single alternated or double row, except in the ventral region in which the row is single for approximately the length of P3. Papillae are simple, small and longer than wide, sub-conical. Sub-marginal papillae are usually absent, but one specimen presents one papilla in the supra-angular region. Jaw sheaths very robust, finely serrated, heavily pigmented distally for about 2/3 to 1/2 their length. The free margin of the upper jaw sheath is widely arch shaped, whereas that of the lower jaw sheath is V-shaped. Labial tooth row formula (LTRF) is 2(2)/3(1). The gap in A2 is wide, almost one third the length of the row, and the anterior edge of the upper jaw sheath is placed within it. The gap in P1 is narrow. The length of P3 is about half the length of the other rows. In two specimens there is a small non medial gap in P2; another specimen presents P2 with a branch fused to P3. The tadpole of P. bibroni belongs to the benthic ecomorphological guild (section II: A: 1) of McDiarmid and Altig (1999) as revised from Altig and Johnston (1989). In tadpoles of P. bibroni the developing lumbar gland can be observed up from stage 41 as a small dark spot (Fig. 5C).

Measurements (in mm): Mean and Standard Deviation (range given in parentheses): TL = 35.4 ± 3.1 (30.0–40.2); BL = 14.8 ± 1.8 (12.6–19.3); TAL = 20.5 ± 3.0 (14.5–24.4); MTH = 8.6 ± 0.6 (7.6–9.4); TMH = 3.1 ± 0.3 (2.7–3.6); TMW = 2.9 ± 0.5 (2.3–3.8); IND = 1.3 ± 0.1 (1.3–1.5); IOD = 4.9 ± 0.3 (4.2–5.8); BMW = 9.3 ± 0.7 (7.9–10.5); BWN = 5.6 ± 0.7 (4.4–6.7); BWE = 8.0 ± 0.7 (6.8–9.2); BMH = 8.7 ± 0.7 (7.6–9.8); RSD = 8.6 ± 0.6 (7.9–10.0); FN = 1.7 ± 0.3 (1.3–2.1); END = 1.5 ± 0.1 (1.3–1.7); N = 0.3 ± 0.1 (0.2–0.5); E = 1.4 ± 0.1 (1.3–1.6); EN= 2.1 ± 0.1 (1.9–2.2); IO = 2.7 ± 0.2 (2.3–3.0); OD = 4.0 ± 0.2 (3.5–4.3); DG = 2.5 ± 0.2 (2.3–2.8); DFH = 2.1 ± 0.1 (1.9–2.3); VFH = 2.0 ± 0.2 (1.6–2.2).

Coloration in life: The body, cephalic region and snout are brownish in dorsal view, with a more intensely pigmented area around the nostrils and a less pigmented one around the eyes. Green and yellowish shines are noticeable with magnification. The pineal end organ is visible between the anterior edges of the orbits as a less pigmented spot. The cephalic region, body and upper half of the abdomen are brownish in lateral view, also with green and yellowish shines. The ventral region is silver with copper shines, the gut is not visible. The gular and branchial regions are transparent, allowing the visualization of the branchial apparatus, heart and head musculature. The dorsal surface of the caudal musculature is brownish along its first third but fades distally; the rest of the tail is light brown with scarce small blotches of melanophores; the caudal musculature in ventral view is pale. Fins are almost transparent, with a fine dark reticulation. Abdominal saccular structure transparent.

Coloration in preservative: Body dark brown in dorsal view, with some less pigmented regions around the eyes. Perinasal regions heavily pigmented. Pineal end organ visible. In lateral view, body dark brown, with the abdomen almost black. Gular and branchial regions and saccular structure transparent. Caudal musculature dark brown, less pigmented at midline for the proximal third. Fins irregularly pigmented, except close to the insertion in the caudal musculature. Caudal blood vessels dark.

Figures

FIGURE 2. Tadpole of Pleurodema bibroni (stage 35) from Barra de Valizas, Department of Rocha, Uruguay (MNHN 7167), in lateral (A) and dorsal (B) views, and tadpole of Pleurodema kriegi (stage 36) from Parador El Cóndor, Pampa de Achala, Province of Córdoba, Argentina (MLP DB 5059), in lateral (C) and dorsal (D) views. Scale bars = 5 mm.

FIGURE 3. (A) Oral disc of a tadpole of Pleurodema bibroni (stage 35) from Barra de Valizas, Department of Rocha, Uruguay (MNHN 7167). (B) Oral disc of a tadpole of Pleurodema kriegi (stage 36) from Parador El Cóndor, Pampa de Achala, Province of Córdoba, Argentina (MLP DB 5059). Scale bars = 1 mm.