siredon

from The Century Dictionary.

• noun A larval salamander; a urodele batrachian with gills, which may subsequently be lost: originally applied to the Mexican axolotl, the larval or gilled form of Amblystoma mexicana, under the impression that it was a distinct genus. See cut under axolotl.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) The larval form of any salamander while it still has external gills; especially, one of those which, like the axolotl (Amblystoma Mexicanum), sometimes lay eggs while in this larval state, but which under more favorable conditions lose their gills and become normal salamanders. See also axolotl.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun zoology The larval form of any salamander while it still has external gills, especially one of those which, like the axolotl, sometimes lay eggs while in this larval state, but which under more favourable conditions lose their gills and become normal salamanders.