Mitochondrial gene tree from RAxML analysis of 16S and cytb sequence data. Asterisks indicate branches with bootstrap proportions >70 for ML analysis and posterior propabilities >95 for Bayesian analysis. Numbers in parentheses after voucher numbers refer to all sampled localities (from Table 1) where haplotype was found. Geographic areas are shown for samples of Bolitoglossa rufescens. Abbreviations: Ch–Chiapas; TMVB–eastern terminus of Trans-Mexican Volcanic Belt; OAX–highlands of northern Oaxaca. Arrows indicate nodes whose daughter lineages are separated by the Isthmus of Tehuantepec.