The larva of Schismaderma carens (Smith, 1849) (Anura: Bufonidae) - a redescription.

We describe the outer morphology of Schismaderma carens larvae in greater detail than previous studies, with special attention to the histology of the unusual head fold in this taxa. The oral cavity is described for the first time. External morphology, including the oral disc (LTRF 2/3), overall shape, biometrical indices, oral cavity morphology, and the filter apparatus confirm that Schismaderma carens is a generalized filter-feeding tadpole, not very different from most toad tadpoles of the world. Internally some papillae around the choanae appear taller and fused than in common toad tadpoles, but their function is unclear. The dorsal horseshoe-shaped head fold is an integumental expansion, rich in blood vessels and surrounded by a thin epithelium consistent with it serving a respiratory function. Its role is interpreted as an additional gas exchange site allowing the utilization of alpha-mesosaprobic and polysaprobic waters. [ABSTRACT FROM AUTHOR]