Only two species of Ixalotriton, I. niger and I. parvus, are currently known, and both are endemic to small regions of Chiapas, México. An additional population of black Ixalotriton has recently been reported from caves on Cerro Baúl, near the only known locality of I. parvus. We conducted morphological and molecular analyses of animals from the new population and I. niger to determine whether they are conspecific. Animals from the Cerro Baúl population resemble I. niger morphologically, but they are somewhat divergent in mitochondrial sequence. We assign them to I. niger because of the lack of diagnostic morphological differences. This expands the range of I. niger to a second locality and puts the two species of Ixalotriton in sympatry, although they are separated by microhabitat. Protection for the new population is urgently needed, given declines in abundance of I. niger at the type locality.