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A new species of hylid frog is described from the southwestern edge of the Mexican Plateau from the states of Morelos and Mexico through Michoacán and Jalisco, reaching the Sierra Madre Occidental in Sinaloa and western Durango. The new species is part of the widespread Mexican hylid Sarcohyla bistincta (sensu amplo) complex, comprised of S. bistincta, S. pentheter, S. calthula, and S. ephemera. One subspecies of S. bistincta (labeculata) was proposed for an isolated population in Oaxaca. We restrict the group's nominal species, S. bistincta (sensu stricto), to the Sierra Madre Oriental of Mexico and southward into the Sierra Madre del Sur of Guerrero and Oaxaca. Examination of type material places S. calthula and S. ephemera in the synonymy of S. labeculata (new combination). The species allied to S. bistincta, namely, S. bistincta, S. labeculata, S. pentheter, and the new species described herein, are diagnosed and described following recent suggested taxonomic changes and new available material.

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Integrative taxonomy has been generally considered as a goal in systematics for more than a decade. Here, we employed environmental, molecular, and morphological data to evaluate the species boundaries within the short-nosed skink Plestiodon brevirostris from south-central Mexico, one member of the morphologically conservative P. brevirostris group. Our molecular dataset includes one mitochondrial and two nuclear loci. The mitochondrial fragment includes the full length of the gene coding for the NADH dehydrogenase subunit 1 protein, a segment of the gene coding for 16S ribosomal RNA, and flanking tRNAs. The nuclear dataset includes fragments of the genes coding for the megakaryoblastic leukemia 1 and RNA fingerprint 35 proteins. We employed phylogenetic reconstruction, analyses of population structure and morphological variation, and species delimitation methods (including the integration of the three kinds of data in a unified probabilistic framework) to evaluate species limits. Our results suggest that P. brevirostris represents four distinct species. The information provided by each kind of data allowed us to discern between alternative explanations for the observed patterns of geographic structure. Two of the newly recognized lineages are poorly differentiated morphologically but apparently differ in environmental preferences and are allopatric. Additionally, one lineage is microendemic and parapatric with respect to another one. Moreover, our phylogenetic analyses suggest that other taxa within the P. brevirostris group may represent species complexes. We discuss our results in the context of integrative species delimitation.

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A new species of Xenosaurus in the X. tzacualtipantecus clade is described from the Sierra Madre Oriental of northern Puebla, Mexico. The new species differs from all of its congeners in possessing a unique combination of characters. The new species appears to be allopatric and fills in the geographic gap between the geographic distributions of X. tzacualtipantecus and the species in the newmanorum clade to the north and northwest and those of the species in the grandis and rackhami clades to the south and southeast. The new species occurs between approximately 880 m and 1470 m of elevation, and appears to be restricted to cloud forest, which has been replaced by coffee plantations in many areas. An updated key to the species of Xenosaurus is provided.

ResumenSe describe una nueva especie de Xenosaurus del clado X. tzacualtipantecus de la Sierra Madre Oriental del norte de Puebla, México. La nueva especie difiere de todos sus congéneres por poseer una combinación única de caracteres. La nueva especie parece ser alopátrica y llena el hueco geográfico entre las distribuciones geográficas de X. tzacualtipantecus y las especies del clado newmanorum hacia el norte y noroeste, y aquellas de las especies de los clados grandis y rackhami hacia el sur y sureste. La nueva especie se ha encontrado en elevaciones entre aproximadamente 880 m y 1470 m y parece estar restringida al bosque mesófilo de montaña, el cual ha sido reemplazado por cafetales en muchas áreas. También se ofrece una clave actualizada para las especies de Xenosaurus.

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We describe a new species of Plestiodon in the P. brevirostris group from the Balsas Basin in central Mexico. It is distinguished from the other species in the group by the following combination of traits: supraoculars four; interparietal enclosed posteriorly by parietals; primary temporal present; seventh supralabial usually contacting upper secondary temporal; longitudinal dorsal scale rows around midbody 23-26; Toe-IV lamellae 13-15; limbs not overlapping when adpressed against body; dorsolateral light line extending posteriorly to level of posterior end of anterior fourth of body or beyond; light median line absent in all growth stages; primary lateral dark lines separated medially by six dorsal scale rows and upper half of adjacent row on each side at level of midbody; lower secondary dark line faint at level of neck; and light coloration of supralabials extending ventrally to lip border. Analyses based on DNA sequences of three loci support the distinctiveness of the new species, as well as its sister species relationship with P. ochoterenae. The Environmental Vulnerability Score of the new species places it in the high vulnerability category.

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We studied type material and freshly collected topotypical specimens to assess the taxonomic status of five names associated with species of Mexican Anolis. We find A. schmidti to be a junior synonym of A. nebulosus, A. breedlovei to be a junior synonym of A. cuprinus, A. polyrhachis to be a junior synonym of A. rubiginosus, A. simmonsi to be a junior synonym of A. nebuloides, and A. adleri to be a junior synonym of A. liogaster.

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We investigate the evolutionary history of the wide-ranging Nearctic treefrog Hyla arenicolor through the integration of extensive range-wide sampling, phylogenetic analyses of multilocus genetic data, and divergence dating. Previous phylogeographic studies of this frog documented a potential signature of introgressive hybridization from an ecologically and morphologically divergent sister species. Based on our Bayesian phylogenetic analyses of mitochondrial DNA, we inferred strong phylogeographic structure in H. arenicolor as indicated by seven well-supported clades, five of which correspond to well-defined biogeographic regions. Clades from the Balsas Basin and southwestern Central Mexican Plateau in Mexico, and the Grand Canyon of Arizona, group with the morphologically, behaviorally, and ecologically divergent mountain treefrogs in the H. eximia group, rendering H. arenicolor as paraphyletic. The phylogenetic position of at least two of these three H. arenicolor clades within the H. eximia group, however, is most likely the result of several episodes of introgressive hybridization and subsequent mitochondrial gene capture separated in time and space, as supported by evidence from the nuclear genes. Hyla arenicolor from the Balsas Basin appear to be deeply divergent from other H. arenicolor and represent a distinctly different species. Results suggests that introgressive hybridization events, both ancient and contemporary, coupled with late Neogene vicariance and Pleistocene climate-driven range shifts, have all played a role in the historical diversification of H. arenicolor.

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Differences in species richness at different elevations are widespread and important for conservation, but the causes of these patterns remain poorly understood. Here, we use a phylogenetic perspective to address the evolutionary and biogeographic processes that underlie elevational diversity patterns within a region. We focus on a diverse but well-studied fauna of tropical amphibians, the hylid frogs of Middle America. Middle American treefrogs show a "hump-shaped" pattern of species richness (common in many organisms and regions), with the highest regional diversity at intermediate elevations. We reconstructed phylogenetic relationships among 138 species by combining new and published sequence data from 10 genes and then used this phylogeny to infer evolutionary rates and patterns. The high species richness of intermediate elevations seems to result from two factors. First, a tendency for montane clades to have higher rates of diversification. Second, the early colonization of montane regions, leaving less time for speciation to build up species richness in lowland regions (including tropical rainforests) that have been colonized more recently. This "time-for-speciation" effect may explain many diversity patterns and has important implications for conservation. The results also imply that local-scale environmental factors alone may be insufficient to explain the high species richness of lowland tropical rainforests, and that diversification rates are lower in earth's most species-rich biome.

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