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Saw scaled vipers of the genus Echis belong to the family Viperidae and subfamily Viperinae. These vipers are widely distributed from East Africa to Southwest and Central Asia. Echis bite is one of the major causes of mortality in the world. Different populations of these medically important snakes have different venom composition, and the relevant antivenom is highly species-specific. Echis has a complex taxonomic history. For many years, only two species were recognized (i.e., Echis coloratus and E. carinatus). Over the past 50 years, the number of species have been raised to 12, of which six species reside in the Middle East. Phylogenetic studies show that the genus Echis fall into four species groups: the E. carinatus, E. coloratus, E. ocellatus and E. pyramidum groups. Until recently, only E. carinatus in Southwest Asia and India and E. coloratus in Arabia were assigned to the Middle East. Several morphological and phylogenetic studies raised the number of Echis species in the Middle East from two to six. These Middle Eastern vipers belong to three different species groups. An Asian, an Arabian and an African group. Distribution and basal split of the genus Echis, likely have been shaped by vicariance and tectonic events, which have separated or connected the land masses. In this study, a brief review on biogeography, taxonomy and distribution of the genus especially in the Middle East is presented. [ABSTRACT FROM AUTHOR]

A new metaheuristic algorithm called green anaconda optimization (GAO) which imitates the natural behavior of green anacondas has been designed. The fundamental inspiration for GAO is the mechanism of recognizing the position of the female species by the male species during the mating season and the hunting strategy of green anacondas. GAO's mathematical modeling is presented based on the simulation of these two strategies of green anacondas in two phases of exploration and exploitation. The effectiveness of the proposed GAO approach in solving optimization problems is evaluated on twenty-nine objective functions from the CEC 2017 test suite and the CEC 2019 test suite. The efficiency of GAO in providing solutions for optimization problems is compared with the performance of twelve well-known metaheuristic algorithms. The simulation results show that the proposed GAO approach has a high capability in exploration, exploitation, and creating a balance between them and performs better compared to competitor algorithms. In addition, the implementation of GAO on twenty-one optimization problems from the CEC 2011 test suite indicates the effective capability of the proposed approach in handling real-world applications. [ABSTRACT FROM AUTHOR]

Objective: The black-headed ground snake, Rhynchocalamus melanocephalus, has a very narrow distribution area in the Hatay province of Turkey. A limited number of reported populations of this snake species is known. The present study aims to show that the distribution area of the species in Turkey can include different parts of the Hatay province or the surrounding provinces. Materials and Methods: One adult individual (1 ♂) was caught from Gözlüce, Yayladağı-Hatay (GPS Data, N: 36° 00' 54.1" and E: 35° 58' 51.6", 66 m a.s.l.). Sex was identified by the absence/presence of palpable hemipenis pockets. The morphometric features of the individual were measured to the nearest 0.01 mm using a digital caliper. Results: According to the literature, the known records of the species in Turkey were only limited to four localities in the Hatay province. The present study provided a new locality (Gözlüce) of the species in the Yayladağı district of the Hatay province. The number of supralabial plates (SRL) is 6-6 and the number of sublabial plates (SL) is 7-7 in the male specimen of Gözlüce. The number of ventral plates (V) is 182 and the number of longitudinal dorsal scale rows at mid-trunk between ventrals (LDS) is 15. Snout-vent length (SVL) is 231.84 mm and tail length (TL) is 50.73 mm. Pholidolial characteristics and morphometric measurements of the Gözlüce specimen were found similar to the other Turkish specimens given in the literature. Conclusion: The new locality record (Gözlüce-Yayladağı) of Rhynchocalamus melanocephalus revealed that the species can also be found in different parts of the Hatay province or in the surrounding provinces. In order to reveal the distribution area of this snake species in Turkey, it is necessary to conduct further field studies in the surrounding areas where the species can potentially spread. [ABSTRACT FROM AUTHOR]

Scuba-divers on tropical coral-reefs often report unprovoked "attacks" by highly venomous Olive sea snakes (Aipysurus laevis). Snakes swim directly towards divers, sometimes wrapping coils around the diver's limbs and biting. Based on a focal animal observation study of free-ranging Olive sea snakes in the southern Great Barrier Reef, we suggest that these "attacks" are misdirected courtship responses. Approaches to divers were most common during the breeding season (winter) and were by males rather than by female snakes. Males also made repeated approaches, spent more time with the diver, and exhibited behaviours (such as coiling around a limb) also seen during courtship. Agitated rapid approaches by males, easily interpreted as "attacks", often occurred after a courting male lost contact with a female he was pursuing, after interactions between rival males, or when a diver tried to flee from a male. These patterns suggest that "attacks" by sea snakes on humans result from mistaken identity during sexual interactions. Rapid approaches by females occurred when they were being chased by males. Divers that flee from snakes may inadvertently mimic the responses of female snakes to courtship, encouraging males to give chase. To prevent escalation of encounters, divers should keep still and avoid retaliation. [ABSTRACT FROM AUTHOR]

The emerging picture of non‐monophyly of scolecophidian snakes is increasingly indicative that fossorial lifestyle, myrmecophagous diet, and miniaturisation are powerful drivers of morphological evolution in squamate skulls. We provide a detailed description of the skull of Xenotyphlops grandidieri, with reference to the skulls of other scolecophidian snakes. The skull, which shows dramatic ventral inflection of the snout complex, is remarkably bizarre, and the mouth opening is more ventrally oriented than in other typhlopoids. The eyes are strongly reduced, and the enlarged and rather flat anterior head shield is covered in numerous sensillae. We put forward several potential explanations for the evolution of these unusual modifications. On the other hand, Xenotyphlops shares numerous synapomorphies with other typhlopoid snakes, including the highly specialized jaw mechanism. We argue that the key differences between the jaw mechanisms of Leptotyphlopidae, Anomalepididae, and Typhlopoidea provide compelling evidence for a strong role of convergence in the evolution of the scolecophidian bauplan, and these clades therefore cannot be interpreted as representative of ancestral anatomy or ecology among snakes. [ABSTRACT FROM AUTHOR]

Many snakes are uniquely adapted to ingest large prey at infrequent intervals. Digestion of large prey is metabolically and aerobically costly, and large prey boluses can impair snake locomotion, increasing vulnerability to predation. Cessation of foraging and use of refugia with microclimates facilitating digestion are expected to be strategies employed by free‐ranging snakes to cope with the demands of digestion while minimizing risk of predation. However, empirical observations of such submergent behavior from field experiments are limited. The brown treesnake (Serpentes: Colubridae: Boiga irregularis) is a nocturnal, arboreal, colubrid snake that was accidentally introduced to the island of Guam, with ecologically and economically costly consequences. Because tools for brown treesnake damage prevention generally rely on snakes being visible or responding to lures or baits while foraging, cessation of foraging activities after feeding would complicate management. We sought to characterize differences in brown treesnake activity, movement, habitat use, and detectability following feeding of large meals (rodents 33% of the snake's unfed body mass) via radio telemetry, trapping, and visual surveys. Compared to unfed snakes, snakes in the feeding treatment group showed drastic decreases in hourly and nightly activity rates, differences in refuge height and microhabitat type, and a marked decrease in detectability by trapping and visual surveys. Depression of activity lasted approximately 5–7 days, a period that corresponds to previous studies of brown treesnake digestion and cycles of detectability. Our results indicate that management strategies for invasive brown treesnakes need to account for cycles of unavailability and underscore the importance of preventing spread of brown treesnakes to new environments where large prey are abundant and periods of cryptic behavior are likely to be frequent. Characterization of postfeeding behavior changes provides a richer understanding of snake ecology and foraging models for species that consume large prey. Many snakes exhibit remarkable physiological adaptations for ingestion of large prey; despite theoretical and laboratory‐based investigations of changes in snake behavior following ingestion of large meals, field experiments documenting such behaviors are limited. We document reduction in movement and changes in refuge site selection by invasive brown treesnakes on the island of Guam following experimental feeding of rodent mass equal to one third of the snake's body mass. These changes in postfeeding movement likely reflect evolution of behaviors favoring predator avoidance and meeting metabolic demands of digestion, and can reduce the effectiveness of invasive snake control tools based on snake foraging behavior for several days after ingesting a large meal. [ABSTRACT FROM AUTHOR]

OBJECTIVE To determine antinociceptive efficacy, behavioral patterns, and respiratory effects associated with dexmedetomidine administration in ball pythons (Py- thon regius). ANIMALS 12 ball pythons. PROCEDURES Antinociception was assessed by applying an infrared heat stimulus to the cranioventral surface of snakes during 2 experiments. Thermal withdrawal latency was measured at 0, 2, and 24 hours after SC injections of dexme- detomidine (0.1 or 0.2 mg/kg) or saline (0.9% NaCI) solution and at 0 to 60 minutes after injection of dexmedetomidine (0.1 mg/kg) or saline solution. Behaviors were recorded at 0, 2, and 24 hours after administration of dex- medetomidine (0.1 mg/kg) or saline solution. Tongue flicking, head flinch to the approach of an observer's hand, movement, and righting reflex were scored. Respiratory frequency was measured by use of plethysmography to detect breathing-related movements after injection of dexmedetomidine (0.1 mg/kg) or saline solution. RESULTS Mean baseline withdrawal latency was 5 to 7 seconds; saline solution did not alter withdrawal latency. Dexmedetomidine increased withdrawal latency by 18 seconds (0.2 mg/kg) and 13 seconds (0.1 mg/kg) above baseline values at 2 hours. Increased withdrawal latency was detected within 15 minutes after dexmedetomidine administration. At 2 hours after injection, there were few differences in behavioral scores. Dexmedetomidine injection de- pressed respiratory frequency by 55% to 70%, compared with results for saline solution, but snakes continued to breathe without prolonged apnea. CONCLUSIONS AND CLINICAL RELEVANCE Dexmedetomidine increased noxious thermal withdrawal latency without causing excessive sedation. Therefore, dexmedetomidine may be a use- ful analgesic drug in ball pythons and other snake species. [ABSTRACT FROM AUTHOR]

Backgrounds: Envenomation is common in Asia including Iran that induces morbidity and mortality. This study investigated the epidemiological characteristics of cases with snake, spider and scorpion bites. Methods: In this cross-sectional design, epidemiologic data of admitted cases to the Toxicology Department of Imam Reza Hospital of Mashhad, Iran were analyzed across a 7-yr period, from 2004 to 2011. SPSS was used for data analysis. Results: This study reports 686 admissions due to animal envenomation with an incidence rate of 2.9 per 100000. Mean (SD, min-max) age of admitted patients was 30 (19, 1-90) yr, and 471 (69%) were male. Snakebite (n, percentage, annual incidence) (299, 44%, 1.3 per 100000) and spider bite (188, 27%, 0.8 per 100000) and scorpion sting (126, 18.4%, 0.5 per 100000) were most frequent cases. Overall, case fatality rate was 0.09 per 100000 which were due to scorpion and unknown bite. No cases of snakebites died in this period. The highest age-specific incidence rate was 4.6 per 100000 and related to 10-20 yr of age. Conclusion: Animal envenomation is frequent in this area and a matter of health concern. While deaths related to snake bite are no longer reported-presumably due to using effective anti-venom - managing unknown and scorpion bites need to be addressed. Envenomation was not overtly an agespecific event in this province. [ABSTRACT FROM AUTHOR]

An important question related to the survival of dehydrating animals is whether feeding provides a net gain of water - contributing postprandial free water and metabolic water - or, alternatively, whether digestion and assimilation of ingested food incur a net loss of water because of requirements for digestion and the excretion of resulting metabolic wastes. Here, I address the question whether voluntary drinking increases or decreases following the ingestion of food. Increased postprandial drinking implies that food consumption increases rather than decreases the requirement for free water, whereas decreased postprandial drinking suggests there is a net profit of water from food. Snakes are ideally suited for such inquiry because they feed intermittently, and the temporal separation of meals allows relatively clear examination of the associated patterns of pre- and postprandial drinking. Voluntary drinking associated with meal consumption was quantified during consecutive feeding trials in four species representing two families of snakes. Postprandial relative to preprandial drinking increased in all four species, indicating that eating increases the physiological requirement for water. These data add to a growing literature pointing to some generality that eating can have negative rather than positive consequences for fluid homeostasis in some dehydrating animals. [ABSTRACT FROM AUTHOR]

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In the present paper color and pattern variations of Hierophis gemonensis, a snake with little morphological variation, are described. For the first time, partially melanistic individuals were observed and described for this species. The identity of one of these snakes was corroborated by genetic means. Taxonomical circumstances and environmental causes of this color and pattern variation are discussed. [ABSTRACT FROM AUTHOR]

The article reports on the oviposition, the act of laying eggs, by Thelotornis kirtlandii snake in an ant nest. Topics mentioned include the importance of thermoregulation in snake to maintain high and balanced body temperatures throughout their active period, the multiple reproduction seasons for snakes, and the incubation of snake eggs.

A letter to the editor is presented regarding the study about the feeding behaviour of Oxyrhopus melanogenys (O. melanogenys) featuring the snake's prey-processing manoeuvre.

Traditional active contour models are hardly convergence to object boundaries where subjective contour and complex background appear. One of the main reasons is because the weighted combination of image energy functions can produce totally different B-Spline snake behaviors. Some efforts have been focused to improve the external energy forces but also lead to higher computational cost. In this research, an approach based on the particle swarm optimization is utilized to control the snake behavior without the necessity of computing the additional information. In the proposed approach, the weighted parameters are optimized using particle swarm optimization by evaluating control points of B-Spline snake in the image energy terms. This method enables the snake to initialize the image energy coefficient automatically and in more convenient way. Experimental results demonstrate that the proposed method can improve the snake behavior.

In rectilinear locomotion, snakes propel themselves by extending or contracting parts of the body. It is interesting that some large snakes will lift the activated part of the body during rectilinear motion. We hypothesize that snakes use this unique strategy named 'lifting behavior" to improve the performance of rectilinear motion on a rough horizontal surface. The purpose of this paper is to examine our hypothesis by examining whether rectilinear motion benefits from lifting behavior. In this study, we derive equations to estimate the energy consumption of rectilinear motion on a simplified 4-link snake robot model. We consider not only mechanical energy dissipation but also heat energy loss during motion. A criterion of minimum energy loss is used as a candidate for the strategy to show how much lifting behavior improves energy efficiency. Our analysis provides a framework for theoretical analysis of the energy cost of rectilinear locomotion for snakes, which can help biologists to further understand the behaviors of snakes. This study also provides some new insights into rectilinear locomotion. [ABSTRACT FROM AUTHOR]

Examination of the geographical variation of selected morphological characters in Philodryas mattogrossensis resulted in evidence to support the recognition of two species and we therefore resurrect P. erlandi from the synonymy of P. mattogrossensis. Philodryas mattogrossensis inhabits Cerrado with some records in Atlantic Forest biomes in eastern Paraguay and southern Brazil, whereas P. erlandi is distributed in dry and arid environments of the Chaco in northern and western Paraguay, southeastern Bolivia, and northern Argentina. We designate SMF 49990 as neotype for Philodryas mattogrossensis. [ABSTRACT FROM AUTHOR]

Toads are chemically defended by bufadienolides, a class of cardiotonic steroids that exert toxic effects by binding to and disabling the Na+/K+- ATPases of cell membranes. Some predators, including a number of snakes, have evolved resistance to the toxic effects of bufadienolides and prey regularly on toads. Resistance in snakes to the acute effects of these toxins is conferred by at least two amino acid substitutions in the cardiotonic steroid binding pocket of the Na+/K+-ATPase. We surveyed 100 species of snakes from a broad phylogenetic range for the presence or absence of resistanceconferring mutations. We found that such mutations occur in a much wider range of taxa than previously believed. Although all sequenced species known to consume toads exhibited the resistance mutations, many of the species possessing the mutations do not feed on toads, much less specialize on that food source. This suggests that either there is little performance cost associated with these mutations or they provide an unknown benefit. Furthermore, the distribution of themutation among major clades of advanced snakes suggests that the origin of the mutation reflects evolutionary retention more than dietary constraint. [ABSTRACT FROM AUTHOR]

Humans and non-human primates are extremely sensitive to snakes as exemplified by their ability to detect pictures of snakes more quickly than those of other animals. These findings are consistent with the Snake Detection Theory, which hypothesizes that as predators, snakes were a major source of evolutionary selection that favored expansion of the visual system of primates for rapid snake detection. Many snakes use camouflage to conceal themselves from both prey and their own predators, making it very challenging to detect them. If snakes have acted as a selective pressure on primate visual systems, they should be more easily detected than other animals under difficult visual conditions. Here we tested whether humans discerned images of snakes more accurately than those of non-threatening animals (e.g., birds, cats, or fish) under conditions of less perceptual information by presenting a series of degraded images with the Random Image Structure Evolution technique (interpolation of random noise). We find that participants recognize mosaic images of snakes, which were regarded as functionally equivalent to camouflage, more accurately than those of other animals under dissolved conditions. The present study supports the Snake Detection Theory by showing that humans have a visual system that accurately recognizes snakes under less discernible visual conditions. [ABSTRACT FROM AUTHOR]

Ability to recognize a risk of predation and react with adaptive antipredatory behavior can enhance fitness, but has some costs as well. Animals can either specifically react on the most dangerous predators (threat-sensitive avoidance) or they have safe but costly general wariness avoiding all potential predators. The level of threat may depend on the predator's foraging ecology and distribution with the prey with sympatric and specialist species being the most dangerous. We used 2 choice trials to investigate antipredatory behavior of captive born and wild-caught leopard geckos confronted with different snake predators from 2 families (Colubridae, Boidae) varying in foraging ecology and sympatric/allopatric distribution with the geckos. Predator-naïve subadult individuals have general wariness, explore both chemically and visually, and perform antipredatory postures toward a majority of snake predators regardless of their sympatry/allopatry or food specialization. The most exaggerated antipredatory postures in both subadult and adult geckos were toward 2 sympatric snake species, the spotted whip snake Hemorrhois ravergieri, an active forager, and the red sand boa Eryx johnii, a subterranean snake with a sit-and-wait strategy. In contrast, also subterranean but allopatric the Kenyan sand boa Eryx colubrinus did not elicit any antipredatory reaction. We conclude that the leopard gecko possesses an innate general antipredatory reaction to different species of snake predators, while a specific reaction to 2 particular sympatric species can be observed. Moreover, adult wild caught geckos show lower reactivity compared with the captive born ones, presumably due to an experience of a real predation event that can hardly be simulated under laboratory conditions. [ABSTRACT FROM AUTHOR]

A study was conducted on the status and diversity of snakes of the Chittagong University Campus (CUC) between September 2013 and December 2014, and on preserved snake specimens of museums of CUC (Department of Zoology, University of Chittagong; Institute of Marine Sciences and Fisheries, University of Chittagong; and Institute of Forestry and Environmental Sciences, University of Chittagong). Thirty-six species of snakes belonging to 22 genera and five families (Typhlopidae, Pythonidae, Colubridae, Elapidae and Viperidae) were recorded from CUC during the study period. Colubridae comprised the highest (24 species i.e., 66.67%) number of species and Pythonidae the lowest (1 species). Checkered Keelback Xenochrophis piscator was the most common snake and the rarest was the Bengalese Kukri Snake Oligodon dorsalis belonging to the family Colubridae. Among venomous snakes Banded Krait Bungarus fasciatus was the most common snake and Black Krait Bungarus niger was the most rare. Their status in CUC has been assessed. [ABSTRACT FROM AUTHOR]

Snakes are important predators that have radiated throughout many ecosystems, and constriction was important in their radiation. Constrictors immobilize and kill prey by using body loops to exert pressure on their prey. Despite its importance, little is known about constriction performance or its full effects on prey. We studied the scaling of constriction performance in two species of giant pythons (Python reticulatus and Python molurus bivittatus) and propose a new mechanism of prey death by constriction. In both species, peak constriction pressure increased significantly with snake diameter. These and other constrictors can exert pressures dramatically higher than their prey's blood pressure, suggesting that constriction can stop circulatory function and perhaps kill prey rapidly by over-pressurizing the brain and disrupting neural function. We propose the latter 'redout effect' as another possible mechanism of prey death from constriction. These effects may be important to recognize and treat properly in rare cases when constrictors injure humans. [ABSTRACT FROM AUTHOR]

Background: Using molecular data generated by high throughput next generation sequencing (NGS) platforms to infer phylogeny is becoming common as costs go down and the ability to capture loci from across the genome goes up. While there is a general consensus that greater numbers of independent loci should result in more robust phylogenetic estimates, few studies have compared phylogenies resulting from smaller datasets for commonly used genetic markers with the large datasets captured using NGS. Here, we determine how a 5-locus Sanger dataset compares with a 377-locus anchored genomics dataset for understanding the evolutionary history of the pseudoxyrhophiine snake radiation centered in Madagascar. The Pseudoxyrhophiinae comprise ∼86 % of Madagascar's serpent diversity, yet they are poorly known with respect to ecology, behavior, and systematics. Using the 377-locus NGS dataset and the summary statistics species-tree methods STAR and MP-EST, we estimated a well-supported species tree that provides new insights concerning intergeneric relationships for the pseudoxyrhophiines. We also compared how these and other methods performed with respect to estimating tree topology using datasets with varying numbers of loci. Methods: Using Sanger sequencing and an anchored phylogenomics approach, we sequenced datasets comprised of 5 and 377 loci, respectively, for 23 pseudoxyrhophiine taxa. For each dataset, we estimated phylogenies using both gene-tree (concatenation) and species-tree (STAR, MP-EST) approaches. We determined the similarity of resulting tree topologies from the different datasets using Robinson-Foulds distances. In addition, we examined how subsets of these data performed compared to the complete Sanger and anchored datasets for phylogenetic accuracy using the same tree inference methodologies, as well as the program *BEAST to determine if a full coalescent model for species tree estimation could generate robust results with fewer loci compared to the summary statistics species tree approaches. We also examined the individual gene trees in comparison to the 377-locus species tree using the program MetaTree. (Continued on next page) Results: Using the full anchored dataset under a variety of methods gave us the same, well-supported phylogeny for pseudoxyrhophiines. The African pseudoxyrhophiine Duberria is the sister taxon to the Malagasy pseudoxyrhophiines genera, providing evidence for a monophyletic radiation in Madagascar. In addition, within Madagascar, the two major clades inferred correspond largely to the aglyphous and opisthoglyphous genera, suggesting that feeding specializations associated with tooth venom delivery may have played a major role in the early diversification of this radiation. The comparison of tree topologies from the concatenated and species-tree methods using different datasets indicated the 5-locus dataset cannot beused to infer a correct phylogeny for the pseudoxyrhophiines under any method tested here and that summary statistics methods require 50 or more loci to consistently recover the species-tree inferred using the complete anchored dataset. However, as few as 15 loci may infer the correct topology when using the full coalescent species tree method BEAST. MetaTree analyses of each gene tree from the Sanger and anchored datasets found that none of the individual gene trees matched the 377-locus species tree, and that no gene trees were identical with respect to topology. Conclusions: Our results suggest that ≥50 loci may be necessary to confidently infer phylogenies when using summaryspecies-tree methods, but that the coalescent-based method BEAST consistently recovers the same topology using only 15 loci. These results reinforce that datasets with small numbers of markers may result in misleading topologies, and further, that the method of inference used to generate a phylogeny also has a major influence on the number of loci necessary to infer robust species trees. [ABSTRACT FROM AUTHOR]

Territorial behaviour, whereby dominant animals gain priority access to critical resources, is widespread in some animal lineages, but rare in others. Theory suggests that territoriality will evolve only when animals can economically defend sites that contain critical resources (typically mates, sometimes food). In striking contrast to their close relatives the lizards, male defence of territories for access to mates has not been reported in snakes. In south-eastern Australia, receptive female small-eyed snakes thermoregulate under 'hot rocks', concentrating mating opportunities and thus, potentially allowing males to enhance their fitness by defending these rocks from rivals. We videotaped staged contests between resident and intruder males and analysed data on cohabitation patterns from a long-term (21 years) mark-recapture study. In staged contests, males actively defended hot rocks from intruder males; and thus, larger males actively displaced their smaller rivals. In the wild, larger males were found under rocks with more or larger females. These results suggest that the thermally driven concentration of female small-eyed snakes has rendered hot rocks economically defensible, and thus favoured the evolution of territoriality in a snake. [ABSTRACT FROM AUTHOR]

Background: The highly derived morphology and astounding diversity of snakes has long inspired debate regarding the ecological and evolutionary origin of both the snake total-group (Pan-Serpentes) and crown snakes (Serpentes). Although speculation abounds on the ecology, behavior, and provenance of the earliest snakes, a rigorous, clade-wide analysis of snake origins has yet to be attempted, in part due to a dearth of adequate paleontological data on early stem snakes. Here, we present the first comprehensive analytical reconstruction of the ancestor of crown snakes and the ancestor of the snake total-group, as inferred using multiple methods of ancestral state reconstruction. We use a combined-data approach that includes new information from the fossil record on extinct crown snakes, new data on the anatomy of the stem snakes Najash rionegrina, Dinilysia patagonica, and Coniophis precedens, and a deeper understanding of the distribution of phenotypic apomorphies among the major clades of fossil and Recent snakes. Additionally, we infer time-calibrated phylogenies using both new 'tip-dating' and traditional node-based approaches, providing new insights on temporal patterns in the early evolutionary history of snakes. Results: Comprehensive ancestral state reconstructions reveal that both the ancestor of crown snakes and the ancestor of total-group snakes were nocturnal, widely foraging, non-constricting stealth hunters. They likely consumed soft-bodied vertebrate and invertebrate prey that was subequal to head size, and occupied terrestrial settings in warm, well-watered, and well-vegetated environments. The snake total-group - approximated by the Coniophis node - is inferred to have originated on land during the middle Early Cretaceous (∼128.5 Ma), with the crown-group following about 20 million years later, during the Albian stage. Our inferred divergence dates provide strong evidence for a major radiation of henophidian snake diversity in the wake of the Cretaceous-Paleogene (K-Pg) mass extinction, clarifying the pattern and timing of the extant snake radiation. Although the snake crown-group most likely arose on the supercontinent of Gondwana, our results suggest the possibility that the snake total-group originated on Laurasia. Conclusions: Our study provides new insights into when, where, and how snakes originated, and presents the most complete picture of the early evolution of snakes to date. More broadly, we demonstrate the striking influence of including fossils and phenotypic data in combined analyses aimed at both phylogenetic topology inference and ancestral state reconstruction. [ABSTRACT FROM AUTHOR]

Assemblage structure, diversity measures and diversity/dominance patterns of snakes were studied between 1996 and 2013 in three types of plantation in the Niger River delta of southern Nigeria. The investigated plantation types were pineapple, banana/plantain, and cassava/yam. Over 74% of the census species ( n = 27) were found in all three plantation types, with, overall, just two singletons ( Bitis nasicornis, Lamprophis olivaceus) being observed. Despite an overall similarity in the taxonomic species composition, a principal component analysis placed the three plantation types in distinct zones of the multivariate space. Diversity/dominance diagrams for the three plantation types showed that banana/plantain and cassava/yam were nearly identical in terms of evenness profile, whereas the pineapple plantation had a higher evenness. [ABSTRACT FROM AUTHOR]

Cottonmouths (Agkistrodon piscivorus) are relatively wide-ranging, North American semi-aquatic pit vipers that frequent edges of water bodies. Although numerous literature accounts describe cottonmouths basking in trees and shrubs at the water's edge, a recent quantitative study in Alabama and Georgia suggests that arboreal behavior by cottonmouths is actually very rare (0.25% of 804 observations). In contrast, I observed frequent arboreal behavior by cottonmouths (42% of 1534 observations) during spring and fall at a southern Illinois wetland. Arboreal basking was particularly frequent in spring (57% of 1049 observations). Frequency of arboreal behavior did not differ between adult and juvenile cottonmouths, but juveniles perched higher than adults. My observations indicate that cottonmouths may frequently be arboreal, at least near the northern limit of their geographic range. Arboreal behavior might facilitate thermoregulation and/or predator avoidance. [ABSTRACT FROM AUTHOR]

The spectral transmittance of the optical media of the eye plays a substantial role in tuning the spectrum of light available for capture by the retina. Certain squamate reptiles, including snakes and most geckos, shield their eyes beneath a layer of offers an added opportunity compared with eyelidded animals for tayloring the spectrum. In particular, the hard scale that covers the surface of the spectacle provides a unique material, keratin, rarely found in vertebrate eyes, a material which may have unique spectral properties. To verify this, shed snake and gecko skins were collected and the spectral transmittance of spectacle scales was spectrophotometrically analyzed. The spec-with a cut-off in the ultraviolet spectrum where taxonomic variation is mostly observed. The spectacle scales of colubrid and elapid snakes were found to exhibit higher cut-off wavelengths than those of pythonids, vipers, and most boids. Gecko spectacle scales in turn exhibited exceptional spectral transmittance through the visual spectrum down into the UV-B. It is suggested that this is due to the absence of beta-keratins in their spectacle scale. [ABSTRACT FROM AUTHOR]

There is growing evidence from both behavioral and neurophysiological approaches that primates are able to rapidly discriminate visually between snakes and innocuous stimuli. Recent behavioral evidence suggests that primates are also able to discriminate the level of threat posed by snakes, by responding more intensely to a snake model poised to strike than to snake models in coiled or sinusoidal postures (Etting and Isbell 2014). In the present study, we examine the potential for an underlying neurological basis for this ability. Previous research indicated that the pulvinar is highly sensitive to snake images. We thus recorded pulvinar neurons in Japanese macaques (Macaca fuscata) while they viewed photos of snakes in striking and non-striking postures in a delayed non-matching to sample (DNMS) task. Of 821 neurons recorded, 78 visually responsive neurons were tested with the all snake images. We found that pulvinar neurons in the medial and dorsolateral pulvinar responded more strongly to snakes in threat displays poised to strike than snakes in non-threat-displaying postures with no significant difference in response latencies. A multidimensional scaling analysis of the 78 visually responsive neurons indicated that threat-displaying and non-threat-displaying snakes were separated into two different clusters in the first epoch of 50 ms after stimulus onset, suggesting bottom-up visual information processing. These results indicate that pulvinar neurons in primates discriminate between poised to strike from those in non-threat-displaying postures. This neuronal ability likely facilitates behavioral discrimination and has clear adaptive value. Our results are thus consistent with the Snake Detection Theory, which posits that snakes were instrumental in the evolution of primate visual systems. [ABSTRACT FROM AUTHOR]

Background: Behaviors involved in courtship and male-male combat have been recorded in a taxonomically broad sample (76 species in five families) of snakes in the clade Boidae + Colubroidea, but before now no one has attempted to find phylogenetic patterns in such behaviors. Here, we present a study of phylogenetic patterns in such behaviors in snakes. Methodology/Principal Findings: From the literature on courtship and male-male combat in snakes we chose 33 behaviors to analyze. We plotted the 33 behaviors onto a phylogenetic tree to determine whether phylogenetic patterns were discernible. We found that phylogenetic patterns are discernible for some behaviors but not for others. For behaviors with discernible phylogenetic patterns, we used the fossil record to determine minimum ages for the addition of each behavior to the courtship and combat behavioral repertoire of each snake clade. Conclusions/Significance: The phylogenetic patterns of behavior reveal that male-male combat in the Late Cretaceous common ancestors of Boidae and Colubridae involved combatants raising the head and neck and attempting to topple each other. Poking with spurs was added in Boidae. In Lampropeltini the toppling behavior was replaced by coiling without neck-raising, and body-bridging was added. Phylogenetic patterns reveal that courtship ancestrally involved rubbing with spurs in Boidae. In Colubroidea, courtship ancestrally involved chin-rubbing and head- or body-jerking. Various colubroid clades subsequently added other behaviors, e.g. moving undulations in Natricinae and Lampropeltini, coital neck biting in the Eurasian ratsnake clade, and tail quivering in Pantherophis. The appearance of each group in the fossil record provides a minimum age of the addition of each behavior to combat and courtship repertoires. Although many gaps in the story of the evolution of courtship and combat in snakes remain, this study is an important first step in the reconstruction of the evolution of these behaviors in snakes. [ABSTRACT FROM AUTHOR]

The status of the material of the genus Gonionotophis from north-eastern Africa (north of Latitude 12'S and east of Longitude 28'E) is reconsidered. The northernmost specimens of G. nyassae (Gunther, 1888) fall within the known range of variation for that species. The available specimens of the G. capensis (A. Smith, 1847) complex from this region indicate that the number of postoculars varies from none to three, so that the 'diagnostic' lack of postoculars in M. fiechteri Scortecci, 1929 is invalid. The Somali specimens should be assigned to the north-eastern form G. chanleri (Stejneger, 1893), of which Simocephalus unicolor Boulenger, 1910 is a synonym. Data for G. chanleri is summarised from throughout its extensive range, and compared with data for adjacent populations of G. capensis and G. savorgnani (Mocquard, 1877). [ABSTRACT FROM AUTHOR]

The article discusses a study conducted on the behavior, rediscoveries and extensions in the geographic distribution of the snake species Xenodon histricus. Topics discussed include the expressions of defensive behavior shown by a specimen of the species during the study, rediscovery of the species in the state of Rio Grande do Sul, Brazil and a map showing the geographic distribution of the species.

Snakes are limbless predators, and many species use venom to help overpower relatively large, agile prey. Snake venoms are complex protein mixtures encoded by several multilocus gene families that function synergistically to cause incapacitation. To examine venom evolution, we sequenced and interrogated the genome of a venomous snake, the king cobra (Ophiophagus hannah), and compared it, together with our unique transcriptome, microRNA, and proteome datasets from this species, with data from other vertebrates. In contrast to the platypus, the only other venomous vertebrate with a sequenced genome, we find that snake toxin genes evolve through several distinct co-option mechanisms and exhibit surprisingly variable levels of gene duplication and directional selection that correlate with their functional importance in prey capture. The enigmatic accessory venom gland shows a very different pattern of toxin gene expression from the main venom gland and seems to have recruited toxin-like lectin genes repeatedly for new nontoxic functions. In addition, tissue-specific microRNA analyses suggested the co-option of core genetic regulatory components of the venom secretory system from a pancreatic origin. Although the king cobra is limbless, we recovered coding sequences for all Hox genes involved in amniote limb development, with the exception of Hoxd12. Our results provide a unique view of the origin and evolution of snake venom and reveal multiple genome-level adaptive responses to natural selection in this complex biological weapon system. More generally, they provide insight into mechanisms of protein evolution under strong selection. [ABSTRACT FROM AUTHOR]

The immunocompetence "pace-of-life" hypothesis proposes that fast-living organisms should invest more in innate immune defenses and less in adaptive defenses compared to slow-living ones. We found some support for this hypothesis in two life-history ecotypes of the snake Thamnophis elegans; fast-living individuals show higher levels of innate immunity compared to slow-living ones. Here, we optimized a lymphocyte proliferation assay to assess the complementary prediction that slow-living snakes should in turn show stronger adaptive defenses. We also assessed the "environmental" hypothesis that predicts that slow-living snakes should show lower levels of immune defenses (both innate and adaptive) given the harsher environment they live in. Proliferation of B- and T-lymphocytes of free-living individuals was on average higher in fast-living than slow-living snakes, opposing the pace-of-life hypothesis and supporting the environmental hypothesis. Bactericidal capacity of plasma, an index of innate immunity, did not differ between fast-living and slow-living snakes in this study, contrasting the previously documented pattern and highlighting the importance of annual environmental conditions as determinants of immune profiles of free-living animals. Our results do not negate a link between life history and immunity, as indicated by eco type-specific relationships between lymphocyte proliferation and body condition, but suggest more subtle nuances than those currently proposed. [ABSTRACT FROM AUTHOR]

A common belief in the southeastern United States is that Cottonmouths (Agkistrodon piscivorus) bask frequently in tree branches over the water's edge and are therefore of considerable hazard for anglers and boaters. Although this notion is almost certainly based upon observations of nonvenomous watersnakes (Nerodia spp.), there are no quantitative data that specifically address this belief. I analyzed a 7-yr dataset on Cottonmouths from two populations (Georgia and Alabama) to determine the frequency of this behavior by Cottonmouths. I recorded behavioral and substrate information for 804 separate observations on Cottonmouths. Only two of these Cottonmouths were exhibiting arboreal behavior (0.25% of observations)-snakes observed over the ground or water surface on branches narrower than their own bodies-confirming that this is indeed a very rare tendency in this species and not likely to be observed by the public. Instead, I frequently encountered Cottonmouths on the ground along the water's edge in their characteristic ambush posture, uncoiled in aquatic situations, or coiled on elevated platforms (e.g., hummocks, piles of driftwood, logs, beaver lodges). This demonstrates that Cottonmouths have the capacity to climb but are not likely to be observed in arboreal situations. [ABSTRACT FROM AUTHOR]

The article discusses the problem of folklore husbandry for exotic animals, specifically reptiles and amphibians, and encourage professional and amateur keepers to apply evidence-based methods to their husbandry routines. Topics discussed include increase in activity and burrowing behavior of snake with the use of a mix of sand, soil and bark chips material; fruits eaten by herbivorous reptile and role of anecdotal observations in development and improvement of husbandry regimes.

We evaluated an automated telemetry system that can dramatically increase the amount of activity and spatial data collected for snakes. We developed methods for analyzing data from single automated receiving units (ARUs) and ARU arrays, compared results from ARUs with conventional hand tracking, and assessed previously untested assumptions used in conventional telemetry, using data from ratsnakes (Pantherophis spp.) in Texas and Illinois. ARU data indicated that ratsnakes spent most of their time in small home ranges (mean = 25 ha) but engaged in forays of up to 1.5 km from their core-use areas, suggesting this species may engage in central place foraging. Forays inflated homerange sizes greatly if areas were estimated using minimum convex polygons rather than 95% kernels. Large numbers of locations generated by ARUs produce more reliable home-range estimates than those from hand tracking. ARU data indicated that snakes moved in response to observers during hand tracking. Daily hand tracking produced reliable estimates of distances moved but underestimated distances by a factor of 4 when snakes were tracked every 5 days. Drawbacks of ARUs are that the error associated with individual locations exceeds that for handtracked locations and that the costs exceed those for hand tracking. Automated receivers can increase data greatly from radio-tracked snakes, providing novel insights unavailable from conventional hand tracking. There are drawbacks to this technology, some of which will vary among study species; therefore, researchers should evaluate the appropriateness of the technology for both the study species and the questions being asked. [ABSTRACT FROM AUTHOR]

Many species exhibit variation in the color of their scales, feathers, or fur. Various forms of natural selection, such as mimicry, crypsis, and species recognition, as well as sexual selection, can influence the evolution of color. Eastern Indigo Snakes (Drymarchon couperi), a federally threatened species, have coloration on the sides of the head and the chin that can vary from black to red or cream. Despite significant conservations efforts for this species, little is known about its biology in the field. Past researchers have proposed that the color variation on the head and chin is associated with the sex of the individual. Alternatively, color might vary among individuals because it is controlled by genes that are under natural selection or neutral evolution. We tested these alternative hypotheses by examining whether coloration of the sublabial, submaxillary, and ventral scales of this species differed by sex or among clutches. We used color spectrometry to characterize important aspects of color in two ways: by examining overall color differences across the entire color spectrum and by comparing differences within the ultraviolet, yellow, and red colorbands. We found that Eastern Indigo Snakes do not exhibit sexual dichromatism, but their coloration does vary among clutches; therefore, the pattern of sexual selection leading to sexual dichromatism observed in many squamates does not appear to play a role in the evolution and maintenance of color variation in Eastern Indigo Snakes. We suggest that future studies should focus on determining whether color variation in these snakes is determined by maternal effects or genetic components and if color is influenced by natural selection or neutral evolutionary processes. Studying species that exhibit bright colors within lineages that are not known for such coloration will contribute greatly to our understanding of the evolutionary and ecological factors that drive these differences. [ABSTRACT FROM AUTHOR]

The article discusses a study on the self-rubbing behavior in psammophiid snakes. As per the study, the self-rubbing behavior in the snake is dependent on temperature. The study also shows that the lipids contained in the nasal secretion of the snake helps it from desiccation by preventing evaporative water loss. The study reveals that a scanning electron microscopy (SEM) analysis of the ultrastructure of psammophiid scales shows that the ultra structure serves to keep the secretion on the scale surface and helps the snake to remain active through out the day. The study also reports the self rubbing behavior in two species of Rhamphiophis namely rostratus and rubro-punctatus.

We describe a new species of Helicops from the southern Amazon Basin in the state of Mato Grosso, Brazil. It differs from all congeners by having dorsal scales in 21/21/19 rows in males and 23/21/19 rows in females, subcaudal keels, a banded dorsal color pattern, and 14-19 ventral blotches. Besides presenting information on the lepidosis and morphometric variation, we also describe the hemipenis and discuss the known distribution of the new species. [ABSTRACT FROM AUTHOR]

It is not clear if rodents express inducible defenses in response to reptilian predators such as snakes. We tested the hypothesis that adult house mice Mus musculus decrease aspects of their reproductive effort upon 1 hour of exposure every 48 hours for a 25-day period to the fecal material and shed skins of a euryphagous ophidian predator, the kingsnake Lampropeltis getula, that had been fed mice. We found no significant differences in the total number of offspring born, the number of pups per litter, and the mean weight of pups in litters born to male and female mice that were exposed to predator cues and those mice that were not exposed to such cues. The lack of an inducible response may be associated with the low cost of an effective defense, or the lack of an effective defense against a generalist snake predator [ABSTRACT FROM AUTHOR]