Snakes and america

Snakes in the family Colubridae include over 2,000 currently recognized species, and comprise roughly 75% of the global snake species diversity on Earth. For such a spectacular radiation, colubrid snakes remain poorly understood ecologically and genetically. Two subfamilies, Colubrinae (788 species) and Dipsadinae (833 species), comprise the bulk of colubrid species richness. Dipsadines are a speciose and diverse group of snakes that largely inhabit Central and South America, with a handful of small-body-size genera that have invaded North America...

BACKGROUND: Dipsadine snakes represent one of the most spectacular vertebrate radiations that have occurred in any continental setting, with over 800 species in South and Central America. Their species richness is paralleled by stunning ecological diversity, ranging from arboreal snail-eating and aquatic eel-eating specialists to terrestrial generalists. Despite the ecological importance of this clade, little is known about the extent to which ecological specialization shapes broader patterns of phenotypic diversity within the group...

Tropidonotus nicobarensis Sclater, 1891 is an enigmatic snake currently referred to the natricine genus Hebius Thompson, 1913. No specimens have been recorded since the original discovery of the name-bearing type in the late 19th century, which was allegedly collected on Kamorta Island in India's Nicobar Archipelago. Recently, a second observation of this species was reported from Havelock Island (Swarajdweep) in the nearby Andaman Archipelago. However, the snake in question is clearly conspecific with another natricine, Thamnophis saurita (Linnaeus, 1766), native to eastern North America...

Snakebite envenoming represents a major health problem in tropical and subtropical countries. Considering the elevated number of accidents and high morbidity and mortality rates, the World Health Organization reclassified this disease to category A of neglected diseases. In Latin America, Bothrops genus snakes are mainly responsible for snakebites in humans, whose pathophysiology is characterized by local and systemic inflammatory and degradative processes, triggering prothrombotic and hemorrhagic events, which lead to various complications, organ damage, tissue loss, amputations, and death...

Predatory innovations impose reciprocal selection pressures upon prey. The evolution of snake venom alpha-neurotoxins has triggered the corresponding evolution of resistance in the post-synaptic nicotinic acetylcholine receptors of prey in a complex chemical arms race. All other things being equal, animals like caecilians (an Order of legless amphibians) are quite vulnerable to predation by fossorial elapid snakes and their powerful alpha-neurotoxic venoms; thus, they are under strong selective pressure. Here, we sequenced the nicotinic acetylcholine receptor alpha-1 subunit of 37 caecilian species, representing all currently known families of caecilians from across the Americas, Africa, and Asia, including species endemic to the Seychelles...

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...

Snake venoms have a complex mixture of compounds that are conserved across species and act synergistically, triggering severe local and systemic effects. Identification of the toxin classes that are most damaging to cell homeostasis would be a powerful approach to focus on the main activities that underpin envenomation. Here, we focus on the venom of Bothrops atrox, snake responsible for most of the accidents in Amazon region of South America. We identified the key cytotoxic toxin fractions from B. atrox venom and mapped their biochemical properties, protein composition and cell damage...

The acanthocephalan Macracanthorhynchus ingens (von Linstow 1879) (Acanthocephala: Archiacanthocephala) is a parasite that infects the gut of carnivores (racoons, coyotes, wolves, foxes, badgers, skunks, opossum, mink and bears) as an adult and the body cavity of lizards, snakes, and frogs as a cystacanth in the Americas. In this study, adults and cystacanths of M. ingens from southeastern Mexico and southern Florida, USA, were identified morphologically by having a cylindrical proboscis armed with 6 rows of hooks each with 6 hooks...

North American Thamnophiini (gartersnakes, watersnakes, brownsnakes, and swampsnakes) are an ecologically and phenotypically diverse temperate clade of snakes representing 61 species across 10 genera. In this study, we estimate phylogenetic trees using ∼3,700 ultraconserved elements (UCEs) for 76 specimens representing 75% of all Thamnophiini species. We infer phylogenies using multispecies coalescent methods and time calibrate them using the fossil record. We also conducted ancestral area estimation to identify how major biogeographic boundaries in North America affect broadscale diversification in the group...

Coevolution has the potential to alter not only the ecological interactions of coevolving partners, but also their interactions with yet other species. The effects of coevolution may ripple throughout networks of interacting species, cascading across trophic levels, swamping competitors, or facilitating survival or reproduction of yet other species linked only indirectly to the coevolving partners. These ripple effects of coevolution may differ among communities, amplifying how the coevolutionary process produces geographic mosaics of traits and outcomes in interactions among species...

BACKGROUND: The venom of Crotalus durissus terrificus, as well as its fractions, has intrigued research groups worldwide who are working to isolate, characterize, and find possible biotechnological applications. A number of studies have elucidated that these fractions and their derivatives possess pharmacological properties, which can enable the development of new drug prototypes with anti-inflammatory, antinociceptive, antitumor, antiviral, and antiparasitic applications. OBJECTIVE: This review presents a systematic study on Crotalus durissus terrificus, the most notable crotalid subspecies in South America, focusing on the composition, toxicological mechanisms, structural aspects, and applications of the main venom toxins (convulxin, gyroxin, crotamine, crotoxin, and their subunits)...

A new species of Dipsas Laurenti, 1768, from Central Panama is described based on molecular analyses, hemipenial morphology, and external characters. This is the sixth species of Dipsas to be described for the country; the snake has been suspected to exist since 1977 and has not been thoroughly studied until now. Additionally, morphological comparations including scale counts are done with other species within the genus, and the current geographic distribution of Dipsastemporalis (Werner, 1909), the sister species, is updated...

INTRODUCTION: Secondary infection is a frequent complication after bites by Bothrops atrox in French Guiana or B. lanceolatus in Martinique. Knowledge of the bacteria present in snake mouths is a valuable aid for determining probabilistic antibiotherapy after Bothrops bite. The objectives of this study were to describe the cultivable bacteria of the oral microbiota of the specimens of B. atrox and B. lanceolatus kept in captivity, and to study their susceptibility to antibiotics. METHODS: Fifteen B...

Among cressdnaviruses, only the family Circoviridae is recognized to infect vertebrates, while many others have unknown hosts. Detection of virus-to-host horizontal gene transfer is useful for solving such virus-host relationships. Here, we extend this utility to an unusual case of virus-to-virus horizontal transfer, showing multiple ancient captures of cressdnavirus Rep genes by avipoxviruses-large dsDNA pathogens of birds and other saurians. As gene transfers must have occurred during virus coinfections, saurian hosts were implied for the cressdnavirus donor lineage...

Ophidiomycosis is an emerging infectious disease caused by the fungus Ophidiomyces ophidiicola (Oo). To date, Oo presence or associated disease condition has been recorded in wild and/or captive snakes from North America, Europe, Asia and Australia, but the data is still scarce outside the Nearctic. Although Italy is a country with a high snake biodiversity in the European panorama, and animals with clinical signs compatible with Oo infection have been documented, to date no investigations have reported the disease in the wild...

Species of the family Reniferidae are trematodes found in the oral cavity and esophagus of snakes from Nearctic and Neotropical regions. Although Renifer heterocoelium has been reported in different snake species from South America, the snails involved in its transmission remain unknown. In this study, a xiphidiocercaria emerged from the physid snail Stenophysa marmorata from Brazil and was subjected to morphological and molecular study. The general morphology, including the shape of the stylet and arrangement of penetration glands, resembles that described for reniferid trematodes from North America...

An irreverent dive into "medical freedom" highlights the comedy and tragedy of medicine in the United States.

Emerging infectious diseases (EIDs) are caused by pathogens that have undergone recent changes in terms of geographic spread, increasing incidence, or expanding host range. In this narrative review, we describe three important fungal EIDs with keratin trophism that are relevant to reptile and amphibian conservation and veterinary practice. Nannizziopsis spp. have been mainly described in saurians; infection results in thickened, discolored skin crusting, with eventual progression to deep tissues. Previously only reported in captive populations, it was first described in wild animals in Australia in 2020...

Snakebite envenomation is a relevant medical hazard in French Guiana and Martinique, two French territories in the Americas. All snakebite envenomations in Martinique are inflicted by the endemic viperid species Bothrops lanceolatus, whereas Bothrops atrox is responsible for the majority of snakebites in French Guiana, although other venomous snake species also occur in this South American territory. This review summarizes some of the key aspects of the natural history of these species, as well as of their venom composition, the main clinical manifestations of envenomations, and their treatment by antivenoms...

We report a case of Spirometra infection in a Samar cobra ( Naja samarensis ) imported from the Philippines, belonging to a zoological collection in the southern United States. Under a poor post-surgical prognosis, the snake was euthanized, and at necropsy plerocercoids of a Diphyllobotriidea were found in its subcutaneous tissues and musculature. Molecular and phylogenetic analyses of the complete cytochrome oxidase c subunit I ( cox1 ) gene of the mitochondrial DNA confirmed that the isolate belonged to the genus Spirometra and was closely related to Spirometra mansoni isolates from Asian countries (bootstrap support = 99...