Comparative anatomy and evolution of the atlantoaxial complex in the fossorial lineage Amphisbaenia (Squamata: Lacertoidea).

The atlas and axis are the first two vertebrae from the cervical series; these two vertebrae are responsible for neck flexion, extension, and rotation movements, while providing insertion points for muscles and tendons. Amphisbaenia is a group of fossorial squamates known for having four distinctive head shapes, which are related to different excavation methods. However, little is known about the relationship between these different digging patterns and the anatomy and evolution of the atlantoaxial complex. In this study, we used computed microtomography data to describe in detail of the atlantoaxial complex for 15 species, belonging to all six current families of Amphisbaenia. Furthermore, we evaluate evolutionary scenarios of selected characters related to the atlantoaxial complex in the most recent phylogeny for Amphisbaenia, using the criteria of parsimony and maximum likelihood. Our results indicate that the evolutionary pattern of the atlantoaxial complex presents a diversification in its morphology that is not always correlated with the shape of the head. This analysis reinforces the hypothesis of remarkable morphological convergences in the evolutionary history of Amphisbaenia. Additionally, some of the characters studied may represent independent evolution through convergence in some cases (e.g., horizontal axis of the neural column) and parallelism in others (e.g., present or absent from the transverse process).

A new species of Oreosaurus (Squamata: Gymnophthalmidae) from the Turimiquire Massif, northeastern Venezuela.

We describe a new species of gymnophthalmid lizard, Oreosaurus bisbali sp. nov., from the Turimiquire Massif in northeastern Venezuela. It is one of three reptile species known to be endemic to the region and the fifth species of Oreosaurus from Venezuela. It can be distinguished from all congeners by a combination of rectangular dorsal scales at midbody, having two scales separating femoral pores medially, and lacking a nasoloreal suture. The new species is likely to be restricted in distribution to the highlands of the Turimiquire Massif, which have been significantly degraded by agriculture.

Long known, brand new, and possibly threatened: a new species of watersnake of the genus Helicops Wagler, 1828 (Serpentes; Xenodontinae) from the Tocantins-Araguaia River Basin, Brazil.

We describe a new species of watersnake of the genus Helicops from the Tocantins-Araguaia River Basin based on characters of coloration and hemipenial morphology, also corroborated by a molecular phylogenetic analysis including 18 terminals of 10 additional congeners. The new species superficially resembles the spotted-patterned He. leopardinus, but differs from it in exhibiting dorsal spots fused into irregular bands, and a unique hemipenial structure with two pairs of distinctly enlarged basal spines. In addition, despite the superficial resemblance of color pattern, our genetic evidence indicates that the new species does not belong to the He. leopardinus radiation, representing the sister group of a component including terminals of this species, He. modestus, and He. infrataeniatus. Finally, we discuss the apparent restriction of the new species to the Tocantins-Araguaia Basin with focus on vicariant processes that may have promoted its differentiation, as well as on the conservation challenges in an area severely affected by anthropic impacts associated with the rapid expansion of hydroelectric and agricultural sectors in the Brazilian Cerrado.

Systematics of Pholidobolus lizards (Squamata, Gymnophthalmidae) from southern Ecuador, with descriptions of four new species.

Four new species of Pholidobolus lizards are described from poorly explored areas in the Andes of southern Ecuador based on morphological and genetic evidence. Among other morphological characters, Pholidobolus samek sp. nov. and P. condor sp. nov. differ from their congeners in having green dorsolateral stripes on head. Males of P. condor sp. nov. differ from those of P. samek sp. nov. in having reddish flanks and venter. P. dolichoderes sp. nov. is distinguished by having a long neck, with more scales between orbit and tympanum, whereas P. fascinatus sp. nov. is distinguished by lacking enlarged medial scales on collar and a conspicuous vertebral stripe. In addition, the phylogenetic position of the new species is inferred using DNA sequences of mitochondrial and nuclear genes. The phylogeny supports strongly monophyly of each of the new species and renders P. macbrydei paraphyletic and split into six subclades. Available data suggest that the new species have restricted distribution ranges (< 100 km2 each), and it is proposed that their classification be as Data Deficient or Critically Endangered species. The results reveal unexpected levels of diversity within Pholidobolus in the Andes of southern Ecuador and highlight the importance of improving scientific collections and conservation efforts in this area.

A species-level total evidence phylogeny of the microteiid lizard family Alopoglossidae (Squamata: Gymnophthalmoidea).

Alopoglossidae is a family of Neotropical lizards composed of 23 species allocated in two genera (Alopoglossus and Ptychoglossus). There is a lack of knowledge about the phylogenetic relationships and systematics of this family. Published phylogenies that include alopoglossid species have very low taxon coverage within the family, and are usually based on limited character sampling. Considering these shortcomings, we infer the phylogenetic relationships of Alopoglossidae-including all but one species in the family-based on the combined analyses of DNA sequences and morphological characters. We use four loci (the mitochondrial 12S, 16S and ND4; the nuclear C-mos) and a matrix of 143 phenotypic characters from scutellation, tongue morphology, hemipenis morphology, and osteology. The dataset is analyzed with Maximum Parsimony, with four alternative weighting schemes: three under Extended Implied Weighting, and one with equal weighting. The respective resulting topologies are compared in a sensitivity analysis framework. Our analyses support the paraphyly of Ptychoglossus, with Alopoglossus nested within it. We provide an updated classification for the family, where Ptychoglossus Boulenger, 1890 is considered a junior synonym of Alopoglossus Boulenger, 1885.

Hemipenial morphology of nine South American species of Mabuya (Scincidae: Lygosominae) with comments on the morphology of the family.

Species of the genus Mabuya are barely recognizable because of their highly conservative external morphology, resulting in unstable systematic and taxonomic status. Considering that hemipenial morphology has been extensively used as a source of systematic information for several groups of Squamata, we described the hemipenial morphology of nine species of Mabuya, searching for diagnostic features useful to taxonomic and systematic studies. To have comparative parameters within the family, we also presented the description of the hemipenes of two other Scincidae species (i.e., Trachylepis atlantica and Tiliqua rugosa). This information, together with the available literature, was analyzed in a comparative framework, allowing us to define some variation for the genus and family. The hemipenial morphology of the species of Mabuya studied is very conservative; features that show subtle variation were the shape of the protuberances present on the asulcate face of the hemipenial body and the presence and type of a lateral fold, on the body. Also, within the family, some variation was found in the shape and length of lobes, length of branches of the sulcus spermaticus, and in the kind of folds and protuberances in both faces of the lobes and hemipenial body. Although these features were not tested in a systematic context, this information suggested variations in hemipenial morphology that could contribute to taxonomic diagnostics and phylogenetic characters. The importance of obtaining proper preparations for gathering accurate information is emphasized, and the use of fresh-killed specimens that shows fewer difficulties for the procedures of preparation is highly recommended.

Chance, luck and a fortunate finding: a new species of watersnake of the genus Helicops Wagler, 1828 (Serpentes: Xenodontinae), from the Brazilian Pantanal wetlands.

We describe a new watersnake of the genus Helicops based on a single specimen found in the northern limit of the Brazilian Pantanal. Immediately after collection, the unique features of color pattern and head proportions prevented us to attribute this specimen to any other congener. Further comparisons revealed that the combination of entire nasal scales, a distinctively acuminate snout, high dorsal and supralabial counts, as well as a dorsal pattern with chain-like spot rows and a venter with vivid and peculiar orange markings confirmed that the specimen represented a new species. Molecular data supported our morphological conclusion recovering the new species deeply nested within Helicops terminals, sister to a clade composed by H. carinicaudus and H. nentur. Our discovery represents a rare instance of a snake species restricted to the Brazilian Pantanal, but we refrain from considering it a Pantanal endemic until further records allow more considerations on distributional patterns.

Phenotypic and life-history diversification in Amazonian frogs despite past introgressions.

The advent of genomics in phylogenetics and population genetics strengthened the perception that conflicts among gene trees are frequent and often due to introgression. However, hybridization occurs mostly among species that exhibit little phenotypic differentiation. A recent study delineating species in Anomaloglossus, a frog genus endemic to the Guiana Shield, identified an intriguing pattern in the A. baeobatrachus species complex. This complex occurs in French Guiana and Amapá (Brazil) and comprises two sympatric phenotypes contrasting not only in body size, habitat, and advertisement call, but also in larval development mode (endotrophic vs exotrophic tadpoles). However, molecular and phenotypic divergences are, in some cases, incongruent, i.e specimens sharing mtDNA haplotypes are phenotypically distinct, suggesting a complex evolutionary history. Therefore, we genotyped 106 Anomaloglossus individuals using ddRADseq to test whether this phenotype/genotype incongruence was a product of phenotypic plasticity, incomplete lineage sorting, multiple speciation events, or admixture. Based on more than 16,000 SNPs, phylogenetic and population genetic approaches demonstrated that exotrophic populations are paraphyletic. Species tree and admixture analyses revealed a strikingly reticulate pattern, suggesting multiple historical introgression events. The evolutionary history of one exotrophic population in northern French Guiana is particularly compelling given that it received genetic material from exotrophic ancestors but shows very strong genetic affinity with the nearby endotrophic populations. This suggests strong selection on larval development and mating call after secondary contact and hybridization. The case of A. baeobatrachus represents a striking example of introgression among lineages that are phenotypically distinct, even in their larval development mode, and highlights how high-resolution genomic data can unravel unexpectedly complex evolutionary scenarios.

Phylogeny of Riama (Squamata: Gymnophthalmidae), impact of phenotypic evidence on molecular datasets, and the origin of the Sierra Nevada de Santa Marta endemic fauna.

Riama is the most speciose genus of the Neotropical lizard family Gymnophthalmidae. Its more than 30 montane species occur throughout the northern Andes, the Cordillera de la Costa (CC) in Venezuela, and Trinidad. We present the most comprehensive phylogenetic analysis of Riama to date based on a total evidence (TE) approach and direct optimization of molecular and morphological evidence. Analyses use DNA sequences from four loci and 35 phenotypic characters. The dataset consists of 55 ingroup terminals representing 25 of the 30 currently recognized species of Riama plus five undescribed taxa, including an endemic species from the Sierra Nevada de Santa Marta (SNSM) in Colombia, and 66 outgroup terminals of 47 species. Analysis results in a well-supported hypothesis in which Riama is polyphyletic, with its species falling into three clades. The Tepuian Anadia mcdiarmidi nests within one clade of Riama, and the recently resurrected Pantodactylus nests within Cercosaura. Accordingly, we propose a monophyletic taxonomy that reflects historical relationships. Analysis of character evolution indicates that the presence/absence of prefrontals-a cornerstone of the early genus-level taxonomy of cercosaurines-is optimally explained as having been plesiomorphically present in the most recent common ancestor of Cercosaurinae and lost in that of the immediately less inclusive clade. Multiple independent reversals to present and subsequent returns to absent occur within this clade. To evaluate the impact of phenotypic evidence on our results, we compare our TE results with results obtained from analyses using only molecular data. Although phenotypic evidence comprises only 1.2% of the TE matrix, its inclusion alters both the topology and support values of the clades that do not differ. Finally, current phylogenetic evidence reveals a SNSM-CC-Trinidad-tepuis biogeographical link. We hypothesize that an ancient connection facilitated the exchange of species between the SNSM and the CC.

A new species of Brasilotyphlus (Gymnophiona: Siphonopidae) and a contribution to the knowledge of the relationship between Microcaecilia and Brasilotyphlus.

A third species of Brasilotyphlus, a siphonopid caecilian, is described based on six specimens from two twin mountains in Roraima state, northern Brazil. Brasilotyphlus dubium sp. nov. differs from all other congeners in having a combination of 123-129 primary annuli and 9-16 secondary annular grooves. The first molecular data were generated and analyzed for Brasilotyphlus, and the genus was recovered as monophyletic and nested within a paraphyletic Microcaecilia. The extent of genetic and taxonomic sampling, and moderate phylogenetic support are not considered sufficient enough to place Brasilotyphlus in the synonymy of Microcaecilia.

Formal recognition of the species of Oreosaurus (Reptilia, Squamata, Gymnophthalmidae) from the Sierra Nevada de Santa Marta, Colombia.

Oreosaurus is one of the two genera extracted from the former Riamasensu lato, which was recently recognized as polyphyletic. Oreosaurus is a small clade (five named and two undescribed species) of montane gymnophthalmid lizards and exhibits an exceptional distributional pattern. Its nominal and undescribed species are discontinuously distributed on the Cordillera de la Costa of Venezuela, the tepuis from the Chimantá massif in Venezuela, the highlands of the island of Trinidad, and the Sierra Nevada de Santa Marta in Colombia (SNSM). Herein, we describe the species of Oreosaurus that is endemic to the SNSM. Historically, this species associates with two names that are currently nomina nuda: Proctoporus serranus and P. specularis. Formal nomenclatural recognition of Oreosaurus serranussp. n. renders specularis a permanently unavailable name for this taxon. Oreosaurus serranussp. n. is the sister of all remaining congeners, and differs primarily from them in having only one pair of genial scales, as well as a unique pattern of scutellation. We provide an identification key to the species of Oreosaurus.

ResumenOreosaurus es uno de los dos géneros que fueron extraídos de Riamasensu lato, el cual fue reconocido recientemente como polifilético. Oreosaurus es un clado pequeño (cinco especies nominales y dos indescritas) de gimnoftálmidos de montaña y presenta un patrón de distribución excepcional. Sus especies nominales e indescritas se distribuyen discontinuamente sobre la Cordillera de la Costa de Venezuela, los tepuyes del macizo de Chimantá en Venezuela, las tierras altas de la isla de Trinidad, y la Sierra Nevada de Santa Marta en Colombia (SNSM). Describimos la especie de Oreosaurus que es endémica de la SNSM. Históricamente, esta especie se asocia con dos nombres que son nomina nuda: Proctoporus serranus y P. specularis. El reconocimiento formal de Oreosaurus serranussp. n. hace que specularis sea un nombre permanentemente indisponible para este taxón. Oreosaurus serranussp. n. es la especie hermana de todos los congéneres restantes, y se diferencia de ellos principalmente por tener un único par de escamas geneiales, así como por presentar un patrón único de escamación. Proveemos una clave de identificación para las especies de Oreosaurus.

Description and phylogenetic relationships of a new genus and two new species of lizards from Brazilian Amazonia, with nomenclatural comments on the taxonomy of Gymnophthalmidae (Reptilia: Squamata).

We describe a new genus and two new species of gymnophthalmid lizards based on specimens collected from Brazilian Amazonia, mostly in the "arc of deforestation". The new genus is easily distinguished from other Gymnophthalmidae by having very wide, smooth, and imbricate nuchals, arranged in two longitudinal and 6-10 transverse rows from nape to brachium level, followed by much narrower, strongly keeled, lanceolate, and mucronate scales. It also differs from all other Gymnophthalmidae, except Iphisa, by the presence of two longitudinal rows of ventrals. The new genus differs from Iphisa by having two pairs of enlarged chinshields (one in Iphisa); posterior dorsal scales lanceolate, strongly keeled and not arranged in longitudinal rows (dorsals broad, smooth and forming two longitudinal rows), and lateral scales keeled (smooth). Maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses based on morphological and molecular data indicate the new species form a clade that is most closely related to Iphisa. We also address several nomenclatural issues and present a revised classification of Gymnophthalmidae.

Two new endangered species of Anomaloglossus (Anura: Aromobatidae) from Roraima State, northern Brazil.

We describe two new species of Anomaloglossus from Roraima State, Brazil, that are likely endemic to single mountains currently isolated among lowland forest and savanna ecosystems. The first species, Anomaloglossus tepequem sp. nov. was collected in 1986 and 1992 along a single stream at >500 m elevation on a tepui-like mountain named Tepequém, but was not detected during recent investigations. It is mainly diagnosed from other Anomaloglossus species by its well developed foot webbing, immaculate cream abdomen colouration and small body size (males: 18.2-20.1 mm, females: 21.7-24.5). The second species, Anomaloglossus apiau sp. nov. was found along several streams between 500 and 1400 m elevation on Serra do Apiaú, and is mainly diagnosed from congeners by its weakly webbed feet, males with swollen third finger and ventrolateral stripe formed by white dots, and its advertisement call; a long trill (up to almost 40 s) consisting of pairs of very short pulses. The discovery of these two apparently microendemic species suggests that additional Anomaloglossus species remain to be described in the Guiana Shield. Both species should be considered critically endangered given their seemingly reduced range size, association with highland habitat, and the anthropogenic pressure they currently face.

A new species of Riama Gray, 1858 (Squamata: Gymnophthalmidae) from the Tropical Andes.

A new species of Riama lizard from the western slopes of the Andes in northern Ecuador is described herein. Morphologically, Riama yumborum sp. nov. can be distinguished from all other congenerics by having an incomplete nasoloreal suture and a cylindrical hemipenial body with diagonally orientated flounces on its lateral aspect. Phylogenetic analyses of mitochondrial and nuclear DNA support the monophyly of the new species and its sister taxon relationship with R. labionis, which occurs allopatrically.

Through the looking glass: the spectacle in gymnophthalmid lizards.

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.

Rediscovery of the earless microteiid lizard Anotosaura collaris Amaral, 1933 (Squamata: Gymnophthalmidae): a redescription complemented by osteological, hemipenial, molecular, karyological, physiological and ecological data.

More than a century after its discovery by Ernest Garbe, and almost 80 years after its original description, we obtained a series of specimens of the earless gymnophthalmid Anotosaura collaris, the type species of the genus, up to now known only by a single specimen. On the basis of the material obtained at and close to the type locality we redescribe the species, adding information about the external and hemipenial morphology, osteology and karytoype. Molecular data confirm its sister relationship with Anotosaura vanzolinia as well as the close relationship of Anotosaura with the Ecpleopodini Colobosauroides and Dryadosaura. We supplement this information with thermophysiological, ecogeographical, karyotypic and ecological data.

A new species of Bachia Gray, 1845 (Squamata: Gymnophthalmidae) from the western Brazilian Amazonia.

A new species of Bachia of the B. dorbignyi group, Bachia scaea sp. nov., is described from the left bank of the upper Madeira River, at Rondônia state, at the western Brazilian Amazonia. The new species resembles morphologically B. dorbignyi and B. peruana, and seems to be related with the former species based on molecular data (16S and c-mos sequences). Nonetheless the presence of a first temporal separating parietal and supralabial scales and the absence of clawed fingers in the new species, can promptly distinguish it from their close relatives. This description ends with several-decades of stasis in the taxonomy of the Bachia dorbignyi group from Amazonian lowlands, and also presents new evidence that supports the Madeira River as a vicariant barrier.