Jefferson's Salamanders have much in common with the more frequently encountered Spotted Salamander. They both emerge from their underground burrows in late winter/early spring, they are ample-sized mole salamanders (although Jefferson's is smaller), and they are both dependant upon vernal pools to reproduce.
However, they have more in common with another mole salamander, the Blue-spotted, with which they often interbreed. It can be very difficult to distinquish pure Jefferson's from hybrids and it often takes DNA samples to solve the mystery.
That said, there are differences in appearence between the two pure populations, most notably in the blue speckling along the sides. In the Jefferson's if it exists at all, is typically more fine - an airbrushed wash of pale gray/blue. Sometimes the salamander is just a chocolate brown, with very little blue on the sides. In the Blue-spotted, the spots are large and distinct. Unfortunately, there are variations in between, in which case the best the lay person can do is assume it is a hybrid or one of the Jefferson's/Blue-spotted Complex.
I have it on good authority, based on a study in the area, the images above and to the left are of a "JJL" Salamander, meaning its genes are 2/3 jeffersonianum and 1/3 laterale. It is, in essence, more Jefferson than Blue-spotted.
One clue that can be used is where the salamander was found. Jeffersons utilize vernal pools which are free from fish, while in Connecticut, Blue-spotteds will breed in larger bodies of water, including red maple swamps, habitats that are not necessarily fish-free. That said, the Blues also use vernal pools. These distinctions are more useful if you find them, or their larvae, in the swamp habitat, in which case you can look more seriously at the possiblity of it being Blue-spotted.
Lastly, the Jeffersons are more restricted in range, not occurring east of the Connecticut River. The Blue-spotteds, while more rare, are found throughout the state (although far from the coast). There are very few pure populations of jeffersonianum or laterele.
Ambystoma jeffersonianum are listed as Special Concern in Connecticut, and should therefore never be collected as pets.
