Ambystoma: (New Latin) representing North American salamanders which are characterized by internal fertilization.

jeffersonianum: named after the location where this salamander was first found (a creek near Jefferson's College in Cannonsburg, Pennsylvania).

What is the Jefferson's complex?

Males and females of this species are diploid (they have 2 copies of 14 chromosomes each, totaling 28 chromosomes 2n = 28) but they may mate with other species to produce hybrid offspring that have extra sets of chromosomes (ie. 3n, 4n, 5n). There are four species in the genus Ambystoma that occasionally hybridize. This group of species is called the Jefferson's complex or Ambystoma laterale-jeffersonianum complex.