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Graphical abstract Highlights • Environmental, molecular, and morphological data were used in a unified framework. • Integrative delimitation allowed to discern between competing hypotheses. • Plestiodon brevirostris is composed of four distinct lineages. • Some of the discovered species are cryptic, microendemic, and/or parapatric. Abstract 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. [ABSTRACT FROM AUTHOR]

Aim The aim of our study was to reconstruct ancestral geographic distributions from time-calibrated phylogenies generated from phylogenomic data to answer three broad questions about the biogeography of skinks in the Plestiodon brevirostris group: (1) Are biogeographic patterns correlated with the formation of the Trans-Mexican Volcanic Belt? (2) Do different methods of phylogenetic estimation result in different topologies? If so, (3) are biogeographic reconstructions impacted by the use of different phylogenetic trees? Location Mexico. Methods We used target enrichment of ultraconserved elements ( UCEs) to obtain sequence data from 58 skinks representing 11 of the 13 described species in the group. We estimated time-calibrated phylogenies using concatenated and multispecies coalescent phylogenetic approaches. We used these phylogenies to reconstruct ancestral geographic distributions. Results The final dataset contained 3,282 UCEs from each skink. Samples of each putative species formed well-supported clades in phylogenetic trees. Time-calibrated phylogenies estimated using concatenated and multispecies coalescent methods were generally congruent, but differed in the placement of one basal relationship. Divergences in the P. brevirostris group were temporally and spatially congruent with the pre-Pleistocene formation of the Trans-Mexican Volcanic Belt. The group most likely colonized the Mexican highlands from east to west during the Late Miocene and Pliocene. Inferences about the early biogeographic history of the group were confounded by the unresolved placement of a key phylogenetic relationship deep in the phylogeny. Conclusions Skinks in the P. brevirostris group represent another example of a widespread montane Mexican taxon with a long history of pre-Pleistocene diversification associated with the primary formation of the Trans-Mexican Volcanic Belt. This mountain range seems to have been both a cradle of diversification for P. brevirostris group species and a land bridge facilitating dispersal across the Mexican highlands. Our results highlight the probable existence of new species within the P. brevirostris complex and suggest that querying a large portion of the genome may be critically important for studying the biogeographic history of these skinks. However, inferred differences between the concatenated and multispecies coalescent phylogenies, and the different biogeographic histories of the P. brevirostris group reconstructed from these phylogenies, caution that methods of estimating phylogenetic trees used in biogeographic reconstructions need to be carefully considered. [ABSTRACT FROM AUTHOR]

A new species of the Geophis dubius group is described from the mountains of the Sierra Zongolica in west-central Veracruz and the Sierra de Quimixtlán in central-east Puebla. The new species is most similar to G. duellmani and G. turbidus, which are endemic to the mountains of northern Oaxaca and the Sierra Madre Oriental of Puebla and Hidalgo, respectively. However, the new species differs from G. duellmani by the presence of postocular and supraocular scales and from G. turbidus by having a bicolor dorsum. With the description of the new species, the species number in the genus increases to 50 and to 12 in the G. dubius group. Additionally, a key to the species of the G. dubius group is provided. [ABSTRACT FROM AUTHOR]

A new species of the colubrid genus Geophis is described from the Sierra Madre del Sur of Guerrero, Mexico. The new species possesses all of the diagnostic characters of the sieboldi group, but differs from all of the other species in the group by having dorsal scales arranged in 17 rows, 133-139 ventrals in females and 130-137 in males, 24-31 subcaudals in females and 34-39 in males, keeled dorsal scales on at least the posterior three-fourths of the body, apparently no apical pits, and a light nuchal collar in juveniles. The new species fills a gap in the distribution of the sieboldi group between Michoacán and Oaxaca, and is the first Mexican species of the genus reported to exhibit both a unicolor (uniformly dark) and a bicolor (with dark markings on a red background color) body and tail dorsal patterns, a polymorphism similar to that previously documented in few lower Central American species. [ABSTRACT FROM AUTHOR]