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Checklist of Amphibian Species and Identification Guide

Identification Terms - Dorsolateral Folds


Many frogs have dorsolateral folds. These are lines of raised glandular skin in an area between the back and the sides. In North American frogs there are usually two (when present) running parallel to the midline of the body, as in the Green Frog to the left. The Bullfrog is an exception in that its dorsolateral folds start behind the eyes and sweep back and down around the ears or tympanic membranes. Knowing this difference can help distinguish adult Green Frogs and Bronze Frogs (Rana clamitans) from young Bullfrogs. These two species overlap considerably both in range and habitat.

Northern Green Frog - Rana clamitans melanota

American Bullfrog - Rana catesbeiana

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