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.
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The oral disc may be Emarginate or Not Emarginate.
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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.
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