The grotto salamander was discovered in 1891 on the
Ozark Plateau, and described by
Leonhard Hess Stejneger in 1892. It is now considered a member of the genus
Eurycea, but was originally described as
Typhlotriton spelaeus. Previously, it was thought to have occurred throughout the Ozark Plateau, but during the mid-20th century, two other species were described from populations formerly assigned to
E. spelaea: the
northern grotto salamander (
E. nerea) of the
Salem Plateau and adjacent
West Springfield Plateau, and the
southern grotto salamander (
E. braggi) of the
East Springfield Plateau. These species were later lumped in with
E. spelaea. However, a 2017 study found all three to be phylogenetically distinct from one another and have deep divergence times dating back to the Late
Miocene;
E. spelaea is thought to be the sister species to the clade comprising
E. nerea and
E. braggi. All three grotto salamanders are thought to descend from an ancestral surface-dwelling form. ==Distribution and habitat==