Leptodactylus knudseni, Heyer, 1972

Schiesari, Luis, Rossa-Feres, Denise De Cerqueira, Menin, Marcelo & Hödl, Walter, 2022, Tadpoles of Central Amazonia (Amphibia: Anura), Zootaxa 5223 (1), pp. 1-149 : 86

Leptodactylus knudseni

External morphology. Description based on five tadpoles at Stages 37 and 38 (LCS 479). Total length 70.2 ± 2.7 mm (N = 5). Body ovoid in dorsal view and globular in lateral view ( Fig. 54A, B ). Snout truncate in dorsal and lateral views. Eyes small, dorsally positioned and dorsolaterally directed. Nostrils small, oval, dorsolaterally positioned near to snout, with opening anterolaterally directed, without a projection on the marginal rim. Oral disc ( Fig. 54C ) anteroventral, non-emarginate; marginal papillae conical, uniseriate and alternate, with a dorsal gap. Submarginal papillae absent. LTRF 2(2)/3 or 2(2)/3(1); A1 and A2 of the same length; P1 and P2 nearly of the same length and longer than P3. Jaw sheaths wide, finely serrated; anterior jaw sheath arch-shaped, posterior jaw sheath V-shaped. Spiracle single, sinistral, conical, short and wide, posterodorsally directed, opening in the medial third of the body, with the centripetal wall fused to the body wall and longer than the external wall. Vent tube medial, fused to the ventral fin, with a medial opening. As typical to tadpoles of L. pentadactylus group, tail long, corresponding to about 68% of total length; caudal musculature of moderate width; in lateral view gradually tapering to a pointed tip. Dorsal fin shallow, originating at the tail-body junction, convex; ventral fin shallow with margin parallel to the ventral margin of caudal musculature. Tail tip pointed. Lateral lines visible.

Colour. In preservative dorsum light to dark grayish-brown; venter beige to light brown opaque; caudal musculature light beige to brown; fins barely translucent to opaque; caudal musculature and fins with or without many small marks. In life dorsum grey, beige or dark olive; venter silver; caudal musculature grey or dark olive; fins transparent (Hero 1990; pers. obs.) to opaque, depending on developmental Stage; tadpoles in advanced developmental stages with dark brown transversal bars between the eyes and in the dorsum ( Fig. 54D, E ).

Variation. LTRF 1/2(1) at Stages 26 and 27, 2(2)/3 or 2(2)/3(1) at Stages 31 to 34. A1 and P3 rows are almost imperceptible at Stages 26 and 27; body less pigmented from Stages 26 to 35, allowing observation of the digestive tract, which is less visible after Stage 36 (Pinto & Menin 2017).

Metamorphs. Metamorphs present a relatively rough skin; dorsal region grayish brown with one brown dorsolateral stripe per sides and well-defined, narrow transversal bars between the eyes and on the dorsum; canthus rostralis brown; venter uniformly white; inguinal region reddish.

Natural history. Large foam nests (~ 15 cm in diameter) are deposited in basins excavated by the males in the margins of shallow, temporary, isolated or streamside ponds in terra-firme forest and forest edge; tadpoles complete the development in the water ( Lima et al. 2012; Pinto & Menin 2017; this study). Clutches contain from 157 to 627 pale yellow eggs (Pinto & Menin 2017). Elongated tadpoles use serpentine locomotion to wriggle in foam and mud. Tadpoles are benthic and camouflaged against the substrate, lightly colored if in muddy ponds with clayish substrate, darkly colored if in clear water with leafy substrate. Tadpoles are found in all months of the year. Tadpole feeding habits include oophagy and necrophagy. Eggs and embryos are preyed upon by ephydrid fly larvae, ants and wasps ( Lacey 1979). Tadpoles are preyed upon by wasps ( Lacey 1979) and Pipa arrabali ( Buchacher 1993) . In experiments eggs were preyed upon by oophagous tadpoles ( Magnusson & Hero 1991) and tadpoles by dragonfly larvae and fish ( Hero 1991; Magnusson & Hero 1991).

Comments. Tadpoles of L. knudseni were described as L. pentadactylus by Duellman (1978) from Ecuador. They differ from those herein characterized by presenting snout rounded in dorsal and lateral views. Tadpoles from Central Amazonia were illustrated by Hero (1990) and differ from those herein characterized by presenting LTRF 2(2)/2-3[1] [2], dorsal fin originating on the tail, and a narrowly rounded tail tip. Heyer & Heyer (2006) characterized tadpoles from Guyana, which differ from those herein characterized by presenting LTRF 2(2)/2-3(1). Moreover, these authors mention that often the lateral and ventrolateral marginal papillae row are alternated in such a way that makes it difficult to determine whether it is a single or double row of papillae.

Figures

FIGURE 54. Tadpole of Leptodactylus knudseni (LCS 479) at Stage 38: (A) lateral view, (B) dorsal view (scale = 10 mm), and (C) oral disc (scale = 1 mm). (D) Dorsolateral view of live tadpole and (E) metamorph.