Phylogenetic relationships and systematic revision of central Texas hemidactyliine plethodontid salamanders

Genetic variation and phylogenetic relationships of central Texas nontransforming spring and cave salamanders, genera Eurycea and Typhlomolge (Plethodontidae: Plethodontinae: Hemidactyliini), were examined using 25 allozyme loci and DNA sequence data for a maximum of 356 bp of the mitochondrial cytochrome b gene. Monophyly of the central Texas hemidactyliines is well supported. High levels of divergence occur among many populations and groups of populations, and there clearly are many more species in the group than previously recognized. Many have extremely restricted distributions in isolated islands of aquatic habitat. Several major monophyletic groups were identified that correspond to geographically circumscribed areas of the Edwards Plateau region. The deepest phylogenetic split in the group occurs between populations northeast versus southwest of the Colorado River. Species that have been assigned to the genus Typhlomolge are phylogenetically nested within the central Texas Eurycea; therefore, the genus Typhlomolge is placed in the synonymy of Eurycea. Continued recognition of the species E. latitans, E. nana, E. neotenes, E. pterophila, E. sosorum, E. tridentifera, and E. troglodytes is recommended, but E. neotenes appears to be restricted in range to a small geographic area, and is not widespread in the region as previously thought. The E. latitans and E. troglodytes species complexes are recognized; each consists of spring and cave populations that include those at the type localities of the latter two species, plus other populations to which they appear most closely related. Three new species from northeast of the Colorado River are described.