The red eft, the terrestrial juvenile stage of the eastern newt, is defended by tetrodotoxin and advertises it with orange colouration. Juvenile red salamanders overlap the eft in range, in habitat and in appearance, and this has long been proposed as a case of Batesian mimicry, where a palatable species gains protection by resembling a defended one.
Experimental work supports the pattern. In predation trials, avian predators previously exposed to efts attacked red salamanders less often than they attacked non-mimetic salamanders, indicating the resemblance transfers learned avoidance. The mimicry is strongest in juveniles, which are the brightest, and fades in older animals as they darken.
The relationship is not clean Batesian mimicry in every account, because red salamanders are themselves distasteful to some predators, which would make it Müllerian instead. Field colouration also varies geographically. The safest statement is that the resemblance is real and confers protection, while the exact category is argued.