Joe, this is a good question. I had also wondered about applying it to other genus but here is my rationale for keeping it only within the Notophthalmus:
1. The term is derived from the Old English word - "efeta" meaning a newt. I do not believe that the word "eft" maintains its current meaning of being a juvenile terrestrial newt outside of the USA (any input from our other English speaking members outside of the USA would help). In the northeast of the USA, it is exclusively applied to the juvenile form of Notophthalmus and to no other newt/salamander that I am aware of. Usually the word "eft" is preceeded by "red" such as a "red eft" Since I was a child, I was taught that the red salamanders with black spots (newts) walking during the day in the forrest were called "red efts" I do not believe that the term has been applied to the terrestrial juveniles of the genus Taricha of the West coast. Has anyone used the word "eft" to refer to an immature Tylototriton, a Triturus or a Cynops?
2. Notophthalmus, as far as I know, has this intermediate stage where the juvenile looks nothing like the sexually mature adult as far as coloration and in its behavior. Even the level of toxicity is greater in the juvenile stage than in the adults.
3. The juvenile efts tend to wander during the day if atmospheric conditions are right while most other juveniles of other genera of salamander are active toward dusk and at night. The orange/red coloration serving as a warning to would be daylight predators that it is highly toxic. In the genus Taricha, the juveniles, while maintaining a dull orange coloration also advertising their toxicity, usually
remain in the same habitat and follow the same behavior as the terrestrial adults .
What do you think?
Louis