The gastromyzophorous tadpoles of Atelopus elegans and A. palmatus (Anura: Bufonidae), with comments on oral and suction structures

The tadpoles of the Neotropical genus Atelopus are only known for 26 out of 96 species described. Here, we describe the tadpoles of A. elegans and A. palmatus including ontogenetic information, measurements, and images of individuals in several stages of growth. Both species are compared with their congeners taking into account some relevant features such as the coloration and relative measurements. Our description focuses on the abdominal sucker and mouth by providing scanning electron microscopy images and comparing the suctorial mechanism with other groups of anurans and fish. We also provide an update to knowledge of the abdominal suckers, and information about their lateral line system and the distribution of their lateral line openings. The results show that brown marks over a tan surface and an irregular distribution of marks along the body and tail are unique to A. elegans; while a patterned distribution of contrasting marks, and the presence of submarginal papillae are unique to A. palmatus. Also, both species show differences in the structures of their teeth. Finally, we conclude that some characters such as coloration, presence or absence of some structures, and relative measurements are useful for identifying the species.