North American Tadpoles

Oral Disc Morphology

Drawing showing oral disc

Tadpoles of certain species may be difficult to distinguish externally. The Oral Disc has characteristics that are useful for distinguishing among similar species.

The following illustrations depict the frontal view of an oral disc as viewed with a dissecting microscope.

Drawing showing anterior labium Drawing showing posterior labium
Drawing showing labial tooth rows Drawing showing jaw sheaths
Drawing showing marginal papillae Drawing showing submarginal papillae

The oral disc may be Emarginate or Not Emarginate.

Drawing showing emarginate Drawing showing not emarginate

Emarginate-a definitive indentation in the margin of the oral disc that persists when disc is open, not a fold

Not Emarginate-lateral margins of disc are not indented when disc is opened

The marginal papillae may be Complete or may have a Dorsal Gap and/or a Ventral Gap.

Drawing showing complete marginal papillae Drawing showing dorsal gap/ventral gap

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