Este trabalho trata do primeiro Squamata (Lacertilia, Teiidae) do Pleistoceno superior do Estado do Rio Grande do Sul, Brasil, e atribuído ao gênero Tupinambis. O material (MCN-PV 2184) é uma hemimandíbula direita, basicrânio, três vértebras dorsais, rádio e ulna esquerdos de um mesmo indivíduo, e provém da Formação Touro Passo, cujos répteis eram antes representados apenas por Testudines. O espécime apresenta as sinapomorfias dos Teiidae e muitas características das espécies recentes de Tupinambis, mas dintingue-se pelo maior tamanho e pelos seguintes caracteres: tubérculo basal mais horizontalizado, dentário e esplenial muito altos, coronóide relativamente baixo, articular com margem ventral marcadamente côncava, e crista adutora muito proeminente, pelo que a face lateral do articular está voltada látero-ventralmente.

Este trabalho trata do primeiro Squamata (Lacertilia, Teiidae) do Pleistoceno superior do Estado do Rio Grande do Sul, Brasil, e atribuído ao gênero Tupinambis. O material (MCN-PV 2184) é uma hemimandíbula direita, basicrânio, três vértebras dorsais, rádio e ulna esquerdos de um mesmo indivíduo, e provém da Formação Touro Passo, cujos répteis eram antes representados apenas por Testudines. O espécime apresenta as sinapomorfias dos Teiidae e muitas características das espécies recentes de Tupinambis, mas dintingue-se pelo maior tamanho e pelos seguintes caracteres: tubérculo basal mais horizontalizado, dentário e esplenial muito altos, coronóide relativamente baixo, articular com margem ventral marcadamente côncava, e crista adutora muito proeminente, pelo que a face lateral do articular está voltada látero-ventralmente.

Este trabalho trata do primeiro Squamata (Lacertilia, Teiidae) do Pleistoceno superior do Estado do Rio Grande do Sul, Brasil, e atribuído ao gênero Tupinambis. O material (MCN-PV 2184) é uma hemimandíbula direita, basicrânio, três vértebras dorsais, rádio e ulna esquerdos de um mesmo indivíduo, e provém da Formação Touro Passo, cujos répteis eram antes representados apenas por Testudines. O espécime apresenta as sinapomorfias dos Teiidae e muitas características das espécies recentes de Tupinambis, mas dintingue-se pelo maior tamanho e pelos seguintes caracteres: tubérculo basal mais horizontalizado, dentário e esplenial muito altos, coronóide relativamente baixo, articular com margem ventral marcadamente côncava, e crista adutora muito proeminente, pelo que a face lateral do articular está voltada látero-ventralmente.

Lacerta agilis is a widespread lizard which reaches the western edge of its range in Britain where it is restricted to three geographically separated areas. Recent habitat loss and fragmentation have resulted in a significant decline and it is now a UK conservation priority. Sand lizards from across the Britain were genotyped at 15 microsatellite loci and the resulting dataset used to address questions regarding the conservation genetics, phylogeography and influence of landscape on patterns of genetic diversity. Genetic diversity of Dorset populations compared favourably to European examples. However, diversity was significantly lower in Surrey and Merseyside. Significant genetic structuring occurred across small geographical distances even in relatively unfragmented landscapes. Lacerta agilis colonised Britain via a land bridge across the North Sea and reached the limits of its current distribution approximately 5,000 years BP. Subsequent climate cooling has resulted in a range contraction to areas where the habitat is suitable for the successful incubation of eggs. A resistance surface was used to investigate the effect of landscape configuration on patterns of genetic diversity at multiple scales in Dorset. At a local scale, habitat type and rivers were the best predictors of genetic diversity. At a regional scale, rivers were most important, whereas habitat type and artificial barriers were less important. Artificial barriers may be more significant than the results suggest as their true effect has not yet been realised due to a genetic time-lag. Male lizards from Merseyside exhibited significant differences in colour and pattern to the Dorset and Surrey populations. However, despite difference in colour, all populations were equally green, which is in keeping with the importance of ‘greenness' as a sexual signal. The implications of these findings for the conservation of L. agilis are discussed in the context of current challenges and predicted future global climate change.

Ecpleopus gaudichaudii Squamata, Gymnophthalmidae) distribuída pelas áreas do Domínio da Mata Atlântica brasileira, é atualmente considerada monotípica. A espécie possui uma aparente homogeneidade morfológica e carece de estudos moleculares e osteológicos na literatura. No presente estudo, faz-se uma análise aprofundada sobre a morfologia do grupo (caracteres quantitativos e qualitativos) e os padrões de variação exibidos através de sua distribuição. Também é feita uma análise das diferenças moleculares em relação ao gene mitocondrial citocromo B entre as diversas populações amostradas. E, por fim, é apresentada uma descrição óssea da espécie. São reconhecidas duas linhagens diferentes com base em uma combinação dos dados morfológicos e moleculares. Os dados moleculares apontam ainda, que a real diversidade do grupo pode ser maior do que aquela demonstrada pelos caracteres morfológicos. Para a determinação da real complexidade taxonômica do grupo faz-se necessários novos testes e estudos de novos genes que permitam uma clarificação melhor das relações entre as populações e linhagens reconhecidas. / Ecpleopus gaudichaudii (Squamata, Gymnophthalmidae), distributed over areas of the Brazilian Atlantic Forest Domain, is the only species allocated in the genus. Despite its apparently homogeneous morphology, morphological and molecular studies approaching the several populations througout the distribution of this species are lacking in the literature. In this study, we provide a thorough morphological analysis involving external features (quantitative and qualitative characters) and osteology of a sample including 183 specimens of Ecpleopus gaudichaudii, in order to assess the patterns of variation throughout its distribution. In addition, a preliminary analysis of molecular differences regarding mitochondrial cytochrome B gene among the populations is also provided. Two different groups are recognized based on a combination of morphological and molecular data. The molecular data also indicate that the actual diversity of the group may be greater than that shown by morphological characters. The ellucidation of the relationships among the populations, as well as of the taxonomy of the group, depends on further studies of molecular approach focusing nuclear and more mithocondrial genes. The results of these studies may provide more solid grounds to future taxonomic reformulations.

Ecpleopus gaudichaudii Squamata, Gymnophthalmidae) distribuída pelas áreas do Domínio da Mata Atlântica brasileira, é atualmente considerada monotípica. A espécie possui uma aparente homogeneidade morfológica e carece de estudos moleculares e osteológicos na literatura. No presente estudo, faz-se uma análise aprofundada sobre a morfologia do grupo (caracteres quantitativos e qualitativos) e os padrões de variação exibidos através de sua distribuição. Também é feita uma análise das diferenças moleculares em relação ao gene mitocondrial citocromo B entre as diversas populações amostradas. E, por fim, é apresentada uma descrição óssea da espécie. São reconhecidas duas linhagens diferentes com base em uma combinação dos dados morfológicos e moleculares. Os dados moleculares apontam ainda, que a real diversidade do grupo pode ser maior do que aquela demonstrada pelos caracteres morfológicos. Para a determinação da real complexidade taxonômica do grupo faz-se necessários novos testes e estudos de novos genes que permitam uma clarificação melhor das relações entre as populações e linhagens reconhecidas. / Ecpleopus gaudichaudii (Squamata, Gymnophthalmidae), distributed over areas of the Brazilian Atlantic Forest Domain, is the only species allocated in the genus. Despite its apparently homogeneous morphology, morphological and molecular studies approaching the several populations througout the distribution of this species are lacking in the literature. In this study, we provide a thorough morphological analysis involving external features (quantitative and qualitative characters) and osteology of a sample including 183 specimens of Ecpleopus gaudichaudii, in order to assess the patterns of variation throughout its distribution. In addition, a preliminary analysis of molecular differences regarding mitochondrial cytochrome B gene among the populations is also provided. Two different groups are recognized based on a combination of morphological and molecular data. The molecular data also indicate that the actual diversity of the group may be greater than that shown by morphological characters. The ellucidation of the relationships among the populations, as well as of the taxonomy of the group, depends on further studies of molecular approach focusing nuclear and more mithocondrial genes. The results of these studies may provide more solid grounds to future taxonomic reformulations.

Reproductive mode has been remarkably labile among squamate reptiles and the evolutionary transition from oviparity to viviparity commonly has been accompanied by a shift in the pattern of embryonic nutrition. Structural specializations for placental transfer of nutrients during intrauterine gestation are highly diverse and many features of the extraembryonic membranes of viviparous species differ markedly from those of oviparous species. However, because of a high degree of evolutionary divergence between the species used for comparisons it is likely that the observed differences arose secondarily to the evolution of viviparity. We studied development of the extraembryonic membranes and placentation in the reproductively bimodal lizard Lacerta vivipara because the influence of reproductive mode on the structural/functional relationship between mothers and embryos can best be understood by studying the most recent evolutionary events. Lecithotrophic viviparity has evolved recently within this species and, although populations with different reproductive modes are allopatric, oviparous and viviparous forms interbreed in the laboratory and share many life history characteristics. In contrast to prior comparisons between oviparous and viviparous species, we found no differences in ontogeny or structure of the extraembryonic membranes between populations with different reproductive modes within L. vivipara. However, we did confirm conclusions from previous studies that the tertiary envelope of the egg, the eggshell, is much reduced in the viviparous population. These conclusions support a widely accepted model for the evolution of squamate placentation. We also found support for work published nearly 80 years ago that the pattern of development of the yolk sac of L. vivipara is unusual and that a function of a unique structure of squamate development, the yolk cleft, is hematopoiesis. The structure of the yolk sac splanchnopleure of L. vivipara is inconsistent with a commonly accepted model for amniote yolk sac function and we suggest that a long standing hypothesis that cells from the yolk cleft participate in yolk digestion requires further study.

BACKGROUND:The extant squamates (>9400 known species of lizards and snakes) are one of the most diverse and conspicuous radiations of terrestrial vertebrates, but no studies have attempted to reconstruct a phylogeny for the group with large-scale taxon sampling. Such an estimate is invaluable for comparative evolutionary studies, and to address their classification. Here, we present the first large-scale phylogenetic estimate for Squamata.RESULTS:The estimated phylogeny contains 4161 species, representing all currently recognized families and subfamilies. The analysis is based on up to 12896 base pairs of sequence data per species (average = 2497 bp) from 12 genes, including seven nuclear loci (BDNF, c-mos, NT3, PDC, R35, RAG-1, and RAG-2), and five mitochondrial genes (12S, 16S, cytochrome b, ND2, and ND4). The tree provides important confirmation for recent estimates of higher-level squamate phylogeny based on molecular data (but with more limited taxon sampling), estimates that are very different from previous morphology-based hypotheses. The tree also includes many relationships that differ from previous molecular estimates and many that differ from traditional taxonomy.CONCLUSIONS:We present a new large-scale phylogeny of squamate reptiles that should be a valuable resource for future comparative studies. We also present a revised classification of squamates at the family and subfamily level to bring the taxonomy more in line with the new phylogenetic hypothesis. This classification includes new, resurrected, and modified subfamilies within gymnophthalmid and scincid lizards, and boid, colubrid, and lamprophiid snakes.

Development of the yolk sac of squamate reptiles (lizards and snakes) differs from other amniote lineages in the pattern of growth of extraembryonic mesoderm, which produces a cavity, the yolk cleft, within the yolk. The structure of the yolk cleft and the accompanying isolated yolk mass influence development of the allantois and chorioallantoic membrane. The yolk cleft of viviparous species of the Eugongylus group of scincid lizards is the foundation for an elaborate yolk sac placenta; development of the yolk cleft of oviparous species has not been studied. We used light microscopy to describe the yolk sac and chorioallantoic membrane in a developmental series of an oviparous member of this species group, Oligosoma lichenigerum. Topology of the extraembryonic membranes of late stage embryos differs from viviparous species as a result of differences in development of the yolk sac. The chorioallantoic membrane encircles the egg of O. lichenigerum but is confined to the embryonic hemisphere of the egg in viviparous species. Early development of the yolk cleft is similar for both modes of parity, but in contrast to viviparous species, the yolk cleft of O. lichenigerum is transformed into a tube-like structure, which fills with cells. The yolk cleft originates as extraembryonic mesoderm is diverted from the periphery of the egg into the yolk sac cavity. As a result, a bilaminar omphalopleure persists over the abembryonic surface of the yolk. The bilaminar omphalopleure is ultimately displaced by intrusion of allantoic mesoderm between ectodermal and endodermal layers. The resulting chorioallantoic membrane has a similar structure but different developmental history to the chorioallantoic membrane of the embryonic hemisphere of the egg.

A prominent scenario for the evolution of viviparity and placentation in reptiles predicts a step-wise pattern with an initial phase of prolonged oviductal egg retention accompanied by progressive reduction in eggshell thickness culminating in viviparity; calcium placentotrophy evolves secondarily to viviparity. Saiphos equalis is an Australian scincid lizard with a reproductive mode that is uncommon for squamates because eggs are retained in the oviduct until late developmental stages, and the embryonic stage at oviposition varies geographically. We studied calcium mobilization by embryos in two populations with different oviductal egg retention patterns to test the hypothesis that the pattern of nutritional provision of calcium is independent of the embryonic stage at oviposition. Females from one population are viviparous and oviposit eggs containing fully formed embryos, whereas embryos in oviposited eggs of the second population are morphologically less mature, and these eggs hatch several days later. The reproductive mode of this population is denoted as prolonged oviductal egg retention. Yolk provided the highest proportion of calcium to hatchlings in both populations. Eggs of both populations were enclosed in calcified eggshells, but shells of the population with prolonged egg retention had twice the calcium content of the viviparous population and embryos recovered calcium from these eggshells. Placental transfer accounted for a substantial amount of calcium in hatchlings in both populations. Hatchling calcium concentration was higher in the population with prolonged egg retention because these embryos mobilized calcium from yolk, the eggshell and the placenta. This pattern of embryonic calcium provision in which both a calcified eggshell and placentotrophy contribute to embryonic nutrition is novel. The reproductive pattern of S. equalis illustrates that calcified eggshells are compatible with prolonged oviductal egg retention and that viviparity is not requisite to calcium placentotrophy.