Patterns, biases and prospects in the distribution and diversity of Neotropical snakes.

Motivation: We generated a novel database of Neotropical snakes (one of the world's richest herpetofauna) combining the most comprehensive, manually compiled distribution dataset with publicly available data. We assess, for the first time, the diversity patterns for all Neotropical snakes as well as sampling density and sampling biases. Main types of variables contained: We compiled three databases of species occurrences: a dataset downloaded from the Global Biodiversity Information Facility (GBIF), a verified dataset built through taxonomic work and specialized literature, and a combined dataset comprising a cleaned version of the GBIF dataset merged with the verified dataset. Spatial location and grain: Neotropics, Behrmann projection equivalent to 1° × 1°. Time period: Specimens housed in museums during the last 150 years. Major taxa studied: Squamata: Serpentes. Software format: Geographical information system (GIS). Results: The combined dataset provides the most comprehensive distribution database for Neotropical snakes to date. It contains 147,515 records for 886 species across 12 families, representing 74% of all species of snakes, spanning 27 countries in the Americas. Species richness and phylogenetic diversity show overall similar patterns. Amazonia is the least sampled Neotropical region, whereas most well-sampled sites are located near large universities and scientific collections. We provide a list and updated maps of geographical distribution of all snake species surveyed. Main conclusions: The biodiversity metrics of Neotropical snakes reflect patterns previously documented for other vertebrates, suggesting that similar factors may determine the diversity of both ectothermic and endothermic animals. We suggest conservation strategies for high-diversity areas and sampling efforts be directed towards Amazonia and poorly known species.

A new species of Imantodes Duméril, 1853 (Serpentes, Dipsadidae) from the Eastern Cordillera of Colombia.

We describe a new species of Imantodes, morphologically similar to I. chocoensis, from the Eastern Cordillera of Colombia. This new species is distinguished from all congeners by the following combination of morphological characters: smooth dorsal scale rows 17/17/15; apical pits absent; infralabials 12-13; ventrals 227-236; subcaudals 147-148; presence of loreal scale; cloacal plate divided; dark temporal stripe on the suture between the lower edge of temporal scales and upper region of supralabials; dorsum of body light brown with dark brown transversal streaks, weakly evident in lateral view; hemipenis in situ extending to the level of 11th subcaudal and reaches the 10th subcaudal when everted; hemipenis with sulcus spermaticus expanded at the base of capitulum and extending distally. Additionally, we discuss the lateral expansion of the sulcus spermaticus in the new species, similar to that of species of Leptodeira.

A new dwarf gecko of the genus Pseudogonatodes (Squamata: Sphaerodactylidae) from the eastern slope of the Andean Cordillera de Mrida in northern South America.

Pseudogonatodes is a poorly known genus of small bodied, diurnal, ground-dwelling geckos widely distributed in northern South America. No additional species have been described in over two decades. Herein we describe a new species from the eastern slope of the Cordillera de Mrida in the Venezuelan Andes. The new species is readily diagnosable morphologically from the other seven recognized species of Pseudogonatodes by having a single postnasal scalea putative autapomorphy. Furthermore, it is characterized by a unique combination of phenotypic characters that includes granular dorsal scales, three large postrostrals, five to six loreals, mental U-shaped, four to six postmentals, 2629 ventrals between anterior levels of fore- and hind limbs, third lamella under fourth toe not distinctly enlarged, and subcaudal pattern 11. In addition to characterizing the external morphology, we present a description of the skull, based on 3D digital models reconstructed from high resolution computed microtomography scans. The discovery of this new species highlights the still underestimated diversity of this group of Neotropical dwarf geckos and underscores the need for further studies on its systematics and taxonomy.

Morphological variation and affinities of the poorly known snake Atractus caxiuana (Serpentes: Dipsadidae) .

Atractus caxiuana was recently described based on three specimens (two males and one female) from the Floresta Nacional de Caxiuanã, municipality of Melgaço, state of Pará, in the eastern portion of the Brazilian Amazon. Apart from the type series, no additional samples are known for the species. In this study, we report new specimens of A. caxiuana, providing new morphological data (meristic, morphometric, pholidosis, colour pattern, and hemipenis) and localities. We relate the variability displayed by the characters analyzed to sexual dimorphism, geographic variation, and ontogeny. Additionally, we provide detailed comparisons with A. collaris and putative sister species, and propose a new species group to accommodate this distinct and possible monophyletic assemblage. 

Unveiling underestimated species diversity within the Central American Coralsnake, a medically important complex of venomous taxa.

Coralsnakes of the genus Micrurus are a diverse group of venomous snakes ranging from the southern United States to southern South America. Much uncertainty remains over the genus diversity, and understanding Micrurus systematics is of medical importance. In particular, the widespread Micrurus nigrocinctus spans from Mexico throughout Central America and into Colombia, with a number of described subspecies. This study provides new insights into the phylogenetic relationships within M. nigrocinctus by examining sequence data from a broad sampling of specimens from Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, and Panama. The recovered phylogenetic relationships suggest that M. nigrocinctus is a species complex originating in the Pliocene and composed of at least three distinct species-level lineages. In addition, recovery of highly divergent clades supports the elevation of some currently recognized subspecies to the full species rank while others may require synonymization.

Taxonomic revision of the Erythrolamprus reginae species group, with description of a new species from Guiana Shield (Serpentes: Xenodontinae).

We perform a review of the Erythrolamprus reginae species group and putative related taxa (E. dorsocorallinus, E. zweifeli, and E. oligolepis), based on external morphology and hemipenial characters. We infer species boundaries among taxa traditionally associated with this group, recognizing two nominal subspecies (Erythrolamprus reginae reginae and E. r. macrosomus) in the species level. We propose the synonymy of E. r. semilineatus with E. reginae and recognize the validity of the related taxa, such as: E. dorsocorallinus, E. zweifeli, and E. oligolepis. In addition, two specimens occurring in the state Amapá, Brazil, are herein described as a new species. Therefore, we provide an identification key for the species of the group and discuss some of the combination of morphological features useful to delimitate the species of this group, in comparison with other representatives of the genus Erythrolamprus.

Taxonomy of the Micrurus spixii species complex (Serpentes, Elapidae).

Historically, the Micrurus spixii species complex comprises four subspecies (M. s. spixii, M. s. martiusi, M. s. obscurus, and M. s. princeps), however, recently, some authors have considered only two full species (M. spixii and M. obscurus). In this paper, we report data on meristic, morphometric, color pattern in life and after preservation, cranial osteology, and hemipenis morphology to Micrurus spixii species complex. We examined 358 specimens throughout the geographical distribution, including the type-series of all taxa. Differences in color pattern and morphology of hemipenis and skull support the existence of only two diagnosable taxa, M. spixii and M. obscurus, both considered here as a full species. We corroborate the synonymy of Micrurus s. martiusi and M. spixii based on wide overlap of meristic and morphometric characters, as well as the similarities of color pattern, hemipenis and skull characters. We can distinguished M. spixii from M. obscurus (in parenthesis) by the combination of the following characters: black cephalic cap (vs. cephalic cap absent, with red parietal region), hemipenial body with spines dispersed on the asulcate surface (vs. spines arranged in rows on the asulcate surface), capitate condition of hemipenis (vs. organ partially-capitate), narrow parietal bone with posterior angular borders (vs. enlarged parietal bone with elliptical posterior border), and relatively long venom inoculating fangs (vs. relatively short venom inoculating fangs).

Species delimitations in the Atractus collaris complex (Serpentes: Dipsadidae).

We reassessed the taxonomic status of the species in the Atractus collaris complex (A. alphonsehogei, A. collaris, A. limitaneus, and A. gaigeae) on the basis of congruence between quantitative and qualitative morphological characters (meristic, morphometric, color pattern, hemipenis, and scale microdematoglyphics) along its wide geographical distribution. Our results support the recognition of three species with apparently fixed diagnostic characters. We propose the synonymization of Atractus limitaneus with A. collaris based on the wide overlap of all morphological character systems here analyzed, as well as on the basis of examination of the holotype and two topotypes of A. limitaneus. Finally, we discuss the geographical variation and morphological distinction of A. alphonsehogei, A. collaris and A. gaigeae. Furthermore, we provide a dichotomous key for all recognized species in the A. collaris species group.

Morphological variation and taxonomy of Atractus latifrons (Günther, 1868) (Serpentes: Dipsadidae).

As currently understood Atractus latifrons is widely distributed in South America, occurring from Suriname to the east of the Andes in Bolivia. Throughout this widespread distribution, at least three distinct color patterns were previously reported in the literature. Here, we test whether quantitative variation and qualitative distribution of morphological characters are correlated with any color pattern displayed by the species along its range. We recognize three aposematic color patterns (bicolor in monads, tricolor in dyads, and tricolor in tetrads) for A. latifrons. We found no obvious correspondence between these patterns and any character systems analyzed herein. Additionally, we redescribe the holotype of A. latifrons and report on morphological variability (meristics, morphometrics, color patterns, and hemipenis) and geographical distribution (extending its distribution to the state Roraima, Brazil) of the species.