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Hydrodynastes bicinctus was described with no type material or locality and it has two subspecies currently recognized that are not taxonomically well defined. We tested the validity of the two subspecies through meristic, morphometric, and color pattern characters. Two apparently distinct color patterns of H. bicinctus were noticed, one from the Cerrado open formations and the other from the Amazon rainforest. These aforementioned patterns, however, exhibited a high degree of geographic overlap and many specimens showed a blended pattern. Based on these results we propose synonymizing H. bicinctus schultzi with the nominal taxon. Furthermore, we designate a neotype for the species, present data on geographic distribution, and provide morphological descriptions of the hemipenis, cephalic glands, and skull.

Sexual dimorphism in snake head/skull is poorly known, although analyses in other vertebrate groups have already pointed this kind of morphological difference. Herein we evaluated the existence of sexual dimorphism in the skull of Xenodon neuwiedii through Geometric Morphometrics (GM). We found that females have larger skulls than males using centroid size data. Considering the ventral view of the palatomaxillary apparatus, compared to females, males tend to have longer maxilla, ectopterygoid slightly laterally shifted, palatine slightly shorter, and longer pterygoid. For the dorsal view, males showed larger snout, more oblique frontoparietal suture, posterior region of the skull more tapered, larger supraoccipital, and larger and more oblique supratemporals. Xenodon neuwiedii showed static allometry only for the symmetric component of the dorsal view, with 9.7% of shape variation explained by size. The present study is the first evaluating and describing sexual dimorphism in skull shape for snakes independently of size. We compared our results with other studies and concluded that to accurately perform intraspecific analyses or to better understand sexual and/or natural selection, sexual dimorphism should be considered, even for structures (e.g. skull) that are traditionally not used for this purpose.

Herein we present a geographical distribution map of Gastrotheca albolineata, an endemic species of marsupial treefrogs from ombrophilous formations in the Atlantic Forest biome. The new records were provided from field observations, collected specimens and data from museum specimens. The present study report new records from Rio de Janeiro state, provide an updated distribution map, and comments on its ecological aspects, thus contributing to future studies concerning the biogeography and biology of this group. Considering the lack of studies on the biology of this species as well as the lack of knowledge on its population trends, we also suggest changes in the status of conservation of the species by the IUCN.

Researchers often use skulls prepared by different techniques in geometric morphometrics (GM). The main goal of this paper was to compare and measure errors in GM analyses using snake skulls prepared with two of these techniques (microCT Scan and chemical maceration). We evaluate if analyses employing skulls with both types of preparation may generate biased results or if this parameter is negligible. Thirty‐four heads of Liophis miliaris merremi were first scanned and subsequently prepared following the techniques of chemical maceration. We used 37 and 18 landmarks for dorsal and ventral views of skulls respectively. To evaluate shape differences between the same skull assessed by microCT Scan and chemical maceration, we performed discriminant analyses, Hotelling's T2 and cross‐validation tests. Discriminant analyses showed significant differences between preparation techniques for both views. However, all the differences between dried and microCT scanned skulls were smaller than those between individuals of the same taxon, which means that such differences are within the range of intraspecific variation. The results support the use of specimens prepared according to both techniques in studies of GM.

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A reliable identification and delimitation of species is an essential pre-requisite for many fields of science and conservation. The Neotropical herpetofauna is the world’s most diverse, including many taxa of uncertain or debated taxonomy. Here we tackle one such species complex, by evaluating the taxonomic status of species currently allocated in the snake genus Xenopholis (X. scalaris, X. undulatus, and X. werdingorum). We base our conclusions on concordance between quantitative (meristic and morphometric) and qualitative (color pattern, hemipenes and skull features) analyses of morphological characters, in combination with ecological niche modeling. We recognize all three taxa as valid species and improve their respective diagnosis, including new data on color in life, pholidosis, bony morphology, and male genitalia. We find low overlap among the niches of each species, corroborating the independent source of phenotypic evidence. Even though all three species occur in the leaf litter of distinct forested habitats, Xenopholis undulatus is found in the elevated areas of the Brazilian Shield (Caatinga, Cerrado and Chaco), whereas X. scalaris occurs in the Amazon and Atlantic rainforests, and X. werdingorum in the Chiquitanos forest and Pantanal wetlands. We discuss the disjunct distribution between Amazonian and Atlantic Forest snake species in the light of available natural history and ecological aspects. This study shows the advantages of combining multiple data sources for reliable identification and circumscription of ecologically similar species.