BackgroundThe retinal pigmented epithelium (RPE) is a rounded shaped structure in almost all lizards. In the New World dwarf geckos, this structure shows an unusual morphology. In addition to this ocular character, we describe notable differences in the development of these geckos in comparison with available developmental staging tables for other geckos and squamate reptiles.ResultsWe identified two main patterns of development of the RPE for squamates. These patterns were mapped onto a metatree of concordant hypotheses of squamates based on molecular data. During post-ovopositional stages the representative species of sphaerodactyls exhibit a RPE layer that transforms gradually from an ovoid form into the generalized spherical form. Sphaerodactyls are the only group of squamates in which this pattern is known.ConclusionsThis transition might be circumstantial evidence that the accessory RPE plays a role in providing additional protection for their apomorphic concaviclivate temporal fovea. We also report the presence of conjunctival papillae in a developmental stage prior to the formation of scleral ossicles. This developmental progression is similar to that of birds and turtles.

In this study we present a list of amphibians and reptiles from the Reserva Biológica do Tapirapé (REBIOTA), an area in the Amazonian rainforest in Pará State, Brazil. We sampled the area for 21 days, in both dry and rainy seasons, using pitfall traps and active searching methods. Our efforts resulted in the discovery of 35 species of amphibians and 27 species of reptiles. This study provides the first list of amphibians and adds eigh new species of reptiles for the Carajás region.

The anatomy and development of the eyelids in squamate reptiles are still relatively unknown, considering its variation within the group. The neotropical Gymnophthalmini are traditionally characterized by having lost the eyelids, but their structure is not well described. In this study, the embryonic development and the adult morphology of the gymnophthalmid eye, with special attention to the eyelids, the nictitating membrane, and the spectacle are described. The eye in some Gymnophthalmini is covered by a spectacle, formed by the embryonic fusion of the dorsal and ventral eyelids, a character possibly synapomorphic to the tribe. The genus Tretioscincus, which floats either as sister to all other Gymnophthalmini, or is nested within the group, is unique in showing functional and movable eyelids. Thus, the presence of functional eyelids can be either considered as the primitive condition for the gymnophthalmini or as a re-acquisition of the character, showing the importance of a well-established phylogenetic hypothesis for understanding morphological evolution. Anat Rec,

ABSTRACT. The systematics of the Americans skinks of the genus Mabuya have been extensively studied, with new arrangements based on molecular analysis. However, the skeletal morphology, their development and ontogenetic variation have been poorly studied in this genus. We described the embryonic skull development of three species of Mabuya and compare it with the African species Trachylepis capensis. We observed that American genus Mabuya presents differences in the skull development, including the pila antotica, orbitosphenoid, vomer, and the basicranial fenestra closure. These morphological differences in Mabuya species may be interpreted as putative synapomorphic characters.RESUMEN. La sistemática del género Mabuya ha sido extensamente estudiada en América y se han propuesto varios arreglos taxonómicos con base en análisis moleculares. Sin embargo, aspectos relacionados con la morfología del esqueleto, su desarrollo y variación ontogenética han sido probrementente estudiados en este género. En el presente trabajo se describe el desarrollo embrionario del cráneo en tres especies del género Mabuya y se compara con el de la especie africana Trachylepis capensis. Se encontró que el género Mabuya presenta diferencias en el desarrollo del cráneo respecto a la especie africana, incluyendo la pila antótica, el orbitosfenoides, el vómer, y el cierre de la fenestra basicraneal. Estas diferencias en el desarrollo del cráneo son importantes, ya que su presencia en todo el género Mabuya sugiere que se podría tratar de sinapomorfias para este  clado.

We provide a review of the geographic range of Chiasmocleis jimi and Proceratophrys concavitympanum and include new records for these rare species in the Reserva Biológica do Tapirapé, southern Pará, Brazil. Our records extend the known distribution of C. jimi and P. concavitympanum in Pará state.

Morphological stasis is generally associated with relative constancy in ecological pressures throughout time, producing strong stabilizing selection that retains similar shared morphology. Although climate and vegetation are commonly the main key factors driving diversity and phenotypic diversification in terrestrial vertebrates, fossorial organisms have their morphology mostly defined by their fossorial lifestyle. Among these secretive fossorial organisms, blind snakes of the South American genus Amerotyphlops are considered poorly studied when compared to other taxa. Here, we evaluate the cryptic diversity of Amerotyphlops using phylogenetic and multivariate approaches. We based our phylogenetic analysis on a molecular dataset composed of 12 gene fragments (eight nuclear and four mitochondrial) for 109 species of Typhlopidae. The multivariate analysis was implemented using 36 morphological variables for 377 specimens of Amerotyphlops. Additionally, we contrast our phylogenetic result with the morphological variation found in cranial, external and hemipenial traits. Our phylogenetic results recovered with strong support the following monophyletic groups within Amerotyphlops: (1) a clade formed by A. tasymicris and A. minuisquamus; (2) a clade composed of A. reticulatus; (3) a north-eastern Brazilian clade including A. yonenagae, A. arenensis, A. paucisquamus and A. amoipira; and (4) a clade composed of A. brongersmianus and a complex of cryptic species. Based on these results we describe four new species of Amerotyphlops from north-eastern and south-eastern Brazil, which can be distinguished from the morphologically similar species, A. brongersmianus and A. arenensis.

No abstract

Anilius scytale is the sister lineage of all other alethinophidian snakes. Morphology of the hind limb complex in adult A. scytale (Aniliidae) has been documented. We herein, for the first time, describe the embryology of the skeletal elements of its hind limb and pelvic girdle and contextualize the evolution of these structures. We identified pregnant females of A. scytale in the Herpetology Collection of the Museu Paraense Emílio Goeldi and separated 40 embryos. The embryos were sequentially staged using external and internal anatomy, collectively comprising a developmental series representing six stages. We cleared‐stained one specimen of stages 31, 34, 36, and 37. Using the embryological information gleaned from A. scytale, we reinterpret evidence relating to the ossification of the pelvis and hindlimbs. In A. scytale hindlimb buds develop as transient structures that developed before Stage 30 and regresses in subsequent stages. There is no external or internal evidence of the forelimb or scapular girdle. From Stage 31 onwards the ischium, pubis, ilium, femur and zeugopodial cartilages are visible. Pubis and femur ossify towards the end of embryonic life, and cloacal spurs do not develop in the embryo. Skeletal elements of the hindlimb and pelvic girdle develop initially in the ventral zone of the cloaca‐tail region. In subsequent stages the hindlimb and pelvic girdle elements migrate dorsally, with the pubis/ischium positioned medial to the ribs. A similar process may be associated with the achievement of the condition of the pelvic girdle in adults of scolecophidians, pythonids and boids.