Such is the case of the Ontario population of the northern dusky salamander. Due to their lack of mobility, some populations of dusky salamander are genetically distinct. The Ouachita dusky salamander occurs in mountainous areas of Arkansas and Oklahoma. The Ouachita dusky salamander grows to about in length including a finned tail. The northern dusky salamander has seasonal variations with its patterns of movement. Being from the family Plethodontidae, the northern dusky salamander is lungless. The Ouachita dusky salamander ("Desmognathus brimleyorum") is a species of salamander in the family Plethodontidae. The northern dusky salamander is the most widespread representative of its genus in Canada. The northern dusky salamander attains sexual maturity at approximately three to four years of age. The Apalachicola dusky salamander ("Desmognathus apalachicolae") is a species of salamander in the family Plethodontidae.