Embryonic development of the neotropical pit viper Bothrops atrox (Serpentes: Viperidae: Crotalinae), with emphasis on pit organ morphogenesis and its evolution in snakes.

BACKGROUND: Bothrops atrox is a pit viper with a loreal pit organ, and its embryological development remains undescribed. Here, we provide a comprehensive description of the embryology of B. atrox, focusing on the loreal pit organ and cephalic scales. RESULTS: We characterized 13 developmental stages of B. atrox based on external features consistent with the embryogenesis of previously described snake species. The loreal pit organ originates from the circumorbital region and migrates to its final position. In Crotalinae, the pit organ first becomes visible at stage 28, whereas in Pythonidae labial, pit organs appear at Stage 35. Pit organs evolved independently three times in Serpentes, encompassing Boidae, Pythonidae, and Crotalinae. Boidae lacks embryological information for pit organs. Furthermore, we observed that head scalation onset occurs at Stage 33 in B. atrox, with fusion of scales surrounding the loreal pit organ. CONCLUSIONS: The embryology of pit organs in Pythonidae and Boidae species remains poorly understood. Our detailed embryological descriptions are critical for proposing developmental scenarios for pit organs and guiding future research on these structures.

Dataset from the Snakes (Serpentes, Reptiles) collection of the Museu Paraense Emílio Goeldi, Pará, Brazil.

BACKGROUND: We present a dataset with information from the snake collection of the Museu Paraense Emílio Goeldi, known as the "Ophidia Collection". This collection currently has 26,728 specimens of snakes, including 9 families, 66 genera and 220 species. For the most part, it represents material from the Amazon Region. Specimens are preserved mostly in wet (alcohol) preparation, with some samples preserved in dry form, as is the case of the shells and skeletons of turtles. The dataset is now available for public consultation on the Global Biodiversity Information Facility portal (https://doi.org/10.15468/lt0wet). NEW INFORMATION: The Herpetological collection of Museu Paraense Emílio Goeldi comprises the largest collection of its kind in the Amazon region with about 100,000 specimens of amphibians and reptiles (chelonians, alligators, lizards, snakes and amphisbaenians). This collection currently has 26,728 specimens of snakes, including 9 families, 66 genera and 220 species, some of which are endemic to the Amazon rainforest region. The Museu Paraense Emílio Goeldi is the second oldest institution of science in Brazil in activity, founded in 1866.

Cranial adaptations for feeding on snails in species of Sibynomorphus (Dipsadidae: Dipsadinae).

Neotropical "goo-eating" dipsadine snakes display a set of morphological and histo-chemical adaptations linked to the capture of their soft-bodied, viscous invertebrate prey. Within this group, species from the genus Sibynomorphus feed chiefly on snails and slugs. Here, we analyzed a series of skull and mandible characters in S. mikanii, S. neuwiedi and S. turgidus using geometric morphometrics, with the aim of assessing morphological adaptations related to slug- and snail-feeding in that genus. We further compared the results with Leptodeira annulata, a species that feeds on vertebrates. To evaluate shape differences of the skull and mandible between species we performed a multivariate analysis of variance and a linear discriminant analysis. Our results show that the narrow, elongate skull in S. mikanii may help with slug ingestion, while asymmetry in teeth number and mandibular shape in S. neuwiedi and S. turgidus are likely related to snail feeding.