Fabio A. Machado

Redescription and Morphological Variation of Oxyrhopus clathratus Duméril, Bibron and Duméril, 1854 (Serpentes: Dipsadidae: Xenodontinae)

ABSTRACT. The snake Oxyrhopus clathratus, which has a restricted distribution within the Atlantic Forest Domain, exhibits great variability in color pattern, shape of the hemipenis, and scalation. The extent of variation has resulted in substantial taxonomic confusion. To date, identification and recognition are problematic, and this is reflected in the synonymy of the species. We examine the type series and specimens from throughout the species distribution to assess intraspecific morphological variation. Morphological variability is correlated with geographical distribution and elevation. Further, we explore whether the morphological data support recognition of more than one species or not. The results suggest that O. clathratus is a single species that exhibits considerable variation in morphology, including three distinct patterns of coloration (melanistic, melanistic with inconspicuous narrow light bands, and with conspicuous dark and light bands alternating along the body) that overlap geographically. The morphology of the ornamented hemipenes varies between “T-shape” and “Y-shape” forms, which occur without any meaningful or elevational structuring. The loreals are usually absent. Based on our results we designate a lectotype for the species.

Taxonomic Status of Chironius multiventris and Chironius cochranae (Serpentes)

Abstract Recently four subspecies of Chironius multiventris were recognized as valid distinct species: C. m. foveatus, C. m. multiventris, C. m. cochranae, and C. m. septentrionalis. Although C. foveatus and C. septentrionalis clearly deserve specific status, a re-evaluation of the characters pointed in the literature as diagnostic of C. multiventris and C. cochranae does not support their recognition as valid distinct taxa. Additionally, our analysis of the scutellation pattern, continuous characters, and hemipenial morphology of 34 specimens, and of the available data in literature, shows that there are no significant differences between them. We therefore suggest that C. cochranae should be synonymized with C. multiventris.

A New Tropidurus (Tropiduridae) from the Semiarid Brazilian Caatinga: Evidence for Conflicting Signal between Mitochondrial and Nuclear Loci Affecting the Phylogenetic Reconstruction of South American Collared Lizards

ABSTRACT Tropidurus Wied, 1825, is one of the most ubiquitous lizard genera distributed in open habitats of tropical and subtropical South America. Nevertheless, the broad representation of specimens of this group in scientific collections is hardly reflected in our knowledge of its taxonomic diversity. Most species currently assigned to Tropidurus began to be uncovered in the early 1980s and additional populations in need of formal taxonomic treatment have been cataloged ever since. Herein, we name Tropidurus sertanejo, n. sp., a new species of the T. torquatus group endemic to the semiarid Brazilian Caatinga. Tropidurus sertanejo, n. sp., is currently known from two isolated populations in the municipalities of Caetité and Ibotirama, State of Bahia, Brazil. This is the only species of the T. torquatus group lacking granular mite pockets on the lateral neck, and it is also diagnosable by having a conspicuous bronze-colored head, a light-brown dorsal body with small pale salmon spots, and small body size in comparison with most congeners. Phylogenetic analyses recovered a paraphyletic Tropidurus, but firmly supported T. sertanejo, n. sp., as member of a monophyletic T. torquatus species group. Trees generated by independent analyses of nuclear and mitochondrial sequence data conflicted with our total evidence phylogenetic hypotheses. Since topological disagreements were detected among phylogenetic trees resulting from maximum parsimony (MP) and maximum likelihood (ML) reconstructions, and MP analyses do not require distinct evolutionary models or partition schemes to be defined prior to conduction of phylogenetic reconstruction, these factors were considered unlikely to explain all the variation in the observed results, favoring the interpretation of conflicting phylogenetic signal. Because detailed information on the distribution, population size, and ecological requirements of T. sertanejo, n. sp., are currently unavailable, we recommend the species to be listed as “data deficient” following the rules proposed by IUCN.

Evolution of morphological integration in the skull of Carnivora (Mammalia): Changes in Canidae lead to increased evolutionary potential of facial traits: EVOLUTION OF INTEGRATION IN CARNIVORA

Morphological integration refers to the fact that different phenotypic traits of organisms are not fully independent from each other, and tend to covary to different degrees. The covariation among traits is thought to reflect properties of the species genetic architecture and thus can have an impact on evolutionary responses. Furthermore, if morphological integration changes along the history of a group, inferences of past selection regimes might be problematic. Here, we evaluated the stability and evolution of the morphological integration of skull traits in Carnivora by using evolutionary simulations and phylogenetic comparative methods. Our results show that carnivoran species are able to respond to natural selection in a very similar way. Our comparative analyses show that the phylogenetic signal for pattern of integration is lower than that observed for morphology (trait averages), and that integration was stable throughout the evolution of the group. That notwithstanding, Canidae differed from other families by having higher integration, evolvability, flexibility, and allometric coefficients on the facial region. These changes might have allowed canids to rapidly adapt to different food sources, helping to explain not only the phenotypic diversification of the family, but also why humans were able to generate such a great diversity of dog breeds through artificial selection.

Origin and hidden diversity within the poorly known Galápagos snake radiation (Serpentes: Dipsadidae)

Galápagos snakes are among the least studied terrestrial vertebrates of the Archipelago. Here, we provide a phylogenetic analysis and a time calibrated tree for the group, based on a sampling of the major populations known to occur in the Archipelago. Our study revealed the presence of two previously unknown species from Santiago and Rábida Islands, and one from Tortuga, Isabela, and Fernandina. We also recognize six additional species of Pseudalsophis in the Galápagos Archipelago (Pseudalsophis biserialis from San Cristobal, Floreana and adjacent islets; Pseudalsophis hoodensis from Española and adjacent islets; Pseudalsophis dorsalis from Santa Cruz, Baltra, Santa Fé, and adjacent islets; Pseudalsophis occidentalis from Fernandina, Isabela, and Tortuga; Pseudalsophis slevini from Pinzon, and Pseudalsophis steindachneri from Baltra, Santa Cruz and adjacent islets). Our time calibrated tree suggests that the genus Pseudalsophis colonized the Galápagos Archipelago through a single event of oceanic dispersion from the coast of South America that occurred at approximately between 6.9u2009Ma and 4.4u2009Ma, near the Miocene/Pliocene boundary.www.zoobank.org/urn:lsid:zoobank.org:pub:2679FD19-01E5-48FE-A0DA-A88FF145DE56