WordNet sense 1 (aquatic North American salamander with red feathery external gills):

Necturus maculosus

WordNet sense 2 (large salamander of North American rivers and streams):

hellbender, Cryptobranchus alleganiensis

WordNet sense 3 (larval salamander of mountain lakes of Mexico that usually lives without metamorphosing):

axolotl, Ambystoma mexicanum