BackgroundThe complex geological history of Mesoamerica provides the opportunity to study the impact of multiple biogeographic barriers on population differentiation. We examine phylogeographic patterns in a clade of lowland salamanders (Bolitoglossa subgenus Nanotriton) using two mitochondrial genes and one nuclear gene. We use several phylogeographic analyses to infer the history of this clade and test hypotheses regarding the geographic origin of species and location of genetic breaks within species. We compare our results to those for other taxa to determine if historical events impacted different species in a similar manner.ResultsDeep genetic divergence between species indicates that they are relatively old, and two of the three widespread species show strong phylogeographic structure. Comparison of mtDNA and nuclear gene trees shows no evidence of hybridization or introgression between species. Isolated populations of Bolitoglossa rufescens from Los Tuxtlas region constitute a separate lineage based on molecular data and morphology, and divergence between Los Tuxtlas and other areas appears to predate the arrival of B. rufescens in other areas west of the Isthmus of Tehuantepec. The Isthmus appears responsible for Pliocene vicariance within B. rufescens, as has been shown for other taxa. The Motagua-Polochic fault system does not appear to have caused population vicariance, unlike in other systems.ConclusionsSpecies of Nanotriton have responded to some major geological events in the same manner as other taxa, particularly in the case of the Isthmus of Tehuantepec. The deep divergence of the Los Tuxtlas populations of B. rufescens from other populations highlights the contribution of this volcanic system to patterns of regional endemism, and morphological differences observed in the Los Tuxtlas populations suggests that they may represent an undescribed species of Bolitoglossa. The absence of phylogeographic structure in B. nympha, in contrast to the other widespread species in the subgenus, may be due to historical forest contraction and more recent range expansion in the region. Phylogeographic data provide substantial insight into the evolutionary history of these morphologically similar species of salamanders, and contribute to our understanding of factors that have generated the high biodiversity of Mesoamerica.

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Se presentan nuevos registros de Sincella incerta en el estado de Chiapas y se confirma su presencia en la región central del estado. Uno de los registros de las estribaciones costeras del sureste llena un espacio en la distribución de la especie entre registros anteriores de Chiapas y Guatemala.

Revista Mexicana de Biodiversidad 86 (2015) 457-468 Biogeography Range extensions of amphibians and reptiles in the southeastern part of the Lacandona rainforest, Mexico Extensión del área de distribución de anfibios y reptiles en la parte sureste de la selva Lacandona, México Abstract The Lacandona rainforest represents one of the most diverse Mexican tropical wet forests. Although some studies have described the amphibians and reptiles of the region, most herpetological lists come from the northern part of the Lacandona, and there are no confirmed records for many of the expected species. We reviewed databases of scientific collections, taxonomy, and published herpetological lists to produce the most recent updated list of amphibian and reptile species in the region (35 amphibians and 90 reptiles). Furthermore, based on recent inventories (2007-2013) we establish 40 range extensions of 8 amphibians and 32 reptiles for the southeastern part of the Lacandona rainforest. Four out of these 40 records confirmed the occurrence of Dermophis mexicanus, Eleutherodactylus leprus, Pantherophis flavirufus, and Bothriechis schlegelii in the region. All Rights Reserved

The snake Mastigodryas dorsalis (Bocourt, 1890) is generally considered absent from Mexico, but a few sources indicate otherwise. Herein we resolve this issue by re-examining a historical specimen and by reporting new records for M. dorsalis in Chiapas, Mexico. These records extend the known distribution of the species 87 km northwest of the nearest pre-existing record in Guatemala. Additionally, based on these new records and an exhaustive literature review, we present an updated distribution for the species and revise its known elevational range to 300–2110 m. A complete Spanish translation of this paper is available in the Supplemental Data. Una traducción completa al español de este artículo está disponible en los Datos Suplementarios.