Snake Fauna Research Articles

Biogeography of the Iranian snakes.

The events of the Cenozoic era such as mountain formation caused Iran to become one of the most amazing biodiversity hotspots in the world today. This pioneering study on Iranian snake biogeography integrates historical and ecological analyses. A phylogeographic review traces speciation and dispersal, while cluster analysis with a new snake checklist assesses faunistic similarities within Iran and its surroundings. Jaccard and Sorenson indices generate similarity dendrograms, Indicator Species Analysis pinpoints regional key species, and Endemism index calculates regional endemism rates, enriching our knowledge of Iran's species diversity. Phylogeographic analyses identify four biogeographical corridors for snake ingress into Iran: the Arabian region through southwestern Iran, the Western Asian mountainous transition zone via northwestern Iran, the Turanian region into northeastern Iran, and the Indus River Valley into southeastern and eastern Iran. Dendrogram analysis divides snake fauna into three groups. The first group associates western Zagros and Khuzestan fauna with the Sahara and Arabian regions. The second group links Kopet Dagh and Turkmen Steppe fauna with the Turanian region, and Central Plateau and Baluchistan fauna with the Iranian region. The third group connects northwest highlands, Alborz and Zagros mountains, and Caspian Sea coasts with the Western Asian Mountain transition zone. The study validates broad biogeographic patterns via ecoregional associations and indicator species analysis, providing finer resolution. Species like Platyceps najadum in Caspian Hyrcanian mixed forests exemplify ecoregional alignment, while Zagros and Alborz mountains exhibit unique faunal indicators, indicating species-level divergence. Shared indicators among widespread ecoregions reflect habitat continuity; exclusive indicators emphasize regional distinctiveness. Despite endemic species prevalence, they seldom act as significant indicators due to various factors. Our research confirms the Zagros Mountains, Khuzestan Plain, Alborz Mountains, and Persian Gulf coasts as snake diversity hotspots, marked by higher species richness compared to other Iranian regions.

Comparing morphology and cranial osteology in two divergent clades of dice snakes from continental Europe (Squamata: Natricidae: Natrix tessellata)

Abstract The Western Palearctic harbours a diverse snake fauna, including numerous endemic species and yet unnamed clades, identified through molecular analyses. However, morphological characteristics of these clades, even of common species, often remain relatively unexplored. In this study, we provide an examination of the morphology and cranial anatomy of the semi-aquatic snake species Natrix tessellata (Laurenti, 1768), with a focus on populations of the so-called ‘Europe’ and ‘Greece’ clades. Utilising both museum collections and field data, we first morphologically examined 541 individuals of N. tessellata, categorising them according to previously established clades and lineages that resulted in relatively low morphometric and meristic variation across the species’ range. When assessing the 448 specimens from the ‘Europe’ and the ‘Greece’ clades separately, we similarly observed little variation in meristic characteristics. On the other hand, individuals of the ‘Greece’ clade displayed smaller and more slender body and head proportions compared to those of the ‘Europe’ clade and the pigmentation of the labial scales is distinctively paler in the ‘Greece’ clade, whereas the overall body colouration remains largely similar between the two. Our osteological analysis of 47 N. tessellata skulls also indicated slight differences in the frontoparietal portion of the braincase between the ‘Europe’ and the ‘Greece’ clades, warranting further examination with a larger dataset and extending to other skull components. These findings hold significance for ongoing enquiries into the species’ biogeography, morphology and ecological adaptations. In summary, the integration of morphological and osteological data with genetic information offers a promising avenue for potential taxonomic revisions of N. tessellata in the future.

Conservation status of Brazilian snakes inhabiting the Atlantic Forest of Northeastern Brazil

Due to the high level of disturbance in natural ecosystems and the progressive loss of habitats resulting from anthropic occupation, biodiversity conservation represents one of the greatest challenges today. Red lists of threatened species are essential tools for identifying species at risk of extinction and guiding conservation efforts. In this study, we assessed the vulnerability to extinction of 55 snake species that occur in the Atlantic Forest of northeastern Brazil in Paraíba state. We developed vulnerability indices based on 12 factors known to influence the survival of snake populations. To analyze the threat profiles and relative risk levels within the snake community, we employed principal component analysis (PCA) and cluster analysis. Additionally, we compared our findings with existing red lists of threatened species. Our results reveal that only 18% of the snake fauna in this region is free of any threat. The aquatic species Helicops angulatus and Oxyrhopus trigeminus were the snakes that presented the lowest risk of extinction, while Caaeteboia gaeli and Crotalus durissus presented the highest risk of extinction. Two groups of species were considered non-threatened and five groups were considered threatened. Our study provides the first overview on the conservation status of snake species in the northern portion of the Atlantic Forest and contributes to a better evaluation of conservation planning for this group in the region.

Addendum to the Fauna of Venomous Snakes of Nakhchivan (Azerbaijan)

The article is devoted to the results of the study of the taxonomic status and ecological characteristics of venomous snake’s species distributed in the territory of the Nakhchivan. Materials for research were collected in various biotopes and landscapes in the highlands during 2011-2023. Information is given on 3 types of poisonous species: Macrovipera lebetina, Montivipera raddei, Pelias eriwanensis.

Factors Influencing Activity and Detection of Species in a Cross Timbers Snake Assemblage

The Cross Timbers of North America is an ecotone between the eastern deciduous forests and central grasslands and exhibits a diverse composite snake fauna. Over a 3-yr period, we performed repeated nocturnal road surveys of snakes across three transects in Wise County, Texas, and evaluated species composition, relative abundances, vehicular mortality, detection probability, and the influence of environmental variables on snake activity. Sixteen taxa and 406 observations were recorded over 250 surveys, and the three most frequently encountered species had detection probabilities of approximately 0.20: Pantherophis obsoletus, Agkistrodon laticinctus, and Nerodia rhombifer. Only the two species of Agkistrodon present at our study area showed significant differences in count frequencies across the three transects. Covariate effects on overall snake activity were subtle, with barometric pressure, ordinal date, and ambient temperature better explaining variation in combined snake counts than humidity, wind speed, or lunar phase. Furthermore, peak snake activity corresponded closely to the timing of peak warm-season precipitation in the study area, suggesting that snake activity coincides with rainfall periodicity in the Cross Timbers region. However, results of site-occupancy models indicated that covariate effects were different across species, and that several common species did not show clear responses to any of the survey covariates.

Rodent Surveys reveal good insights into the Snake Fauna in an Agro-Pastoral Ecosystem in Southern India

Rats and mice are among the foremost of agricultural pests that are plentiful in farmlands. Snakes are one of the most specialized natural rat-controlling predatory species, also equally prevalent in farmlands. We studied the snake fauna of agroecosystem in south-eastern India by gathering concomitant data on snakes, during rodent surveys wherein rodents were the main target taxa. From a one year long day-and-night survey focusing on rodents, we obtained 151 sightings of snakes belonging to 22 species (four of which are venomous). A total of 66 sightings representing 14 species were obtained in diurnal surveys, and 21 sightings representing 7 species were obtained in night surveys. As much as 64 sightings representing 20 species were obtained by chance encounters in the study site, but outside of the designated rodent survey duration. An uncommon snake Sibynophis subpunctatus was recorded. The colubrid Ptyas mucosa was the commonest encountered species during the day while at night it was the viper Echis carinatus. Estimated species diversity in Shannon-Wiener index was H = 1.218.

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Saberes y leyendas: El etnoconocimiento como herramienta para mejorar la convivencia entre serpientes y pobladores del sur de la Región Chaqueña (Córdoba, Argentina)

In the northwest of Córdoba, snakes accidents constitute a significant problem to the inhabitants of small rural communities because they live and work in the environments where snakes live. Therefore, it is relevant to study and know the perception and ancestral knowledge of the inhabitants of this area in relation to the snake fauna, as to properly diagnose this problem in a regional framework, and thus be able to carry out activities to prevent ophidian accidents. We performed interviews related to the knowledge of the snakes in the area, the popular nomenclature, the use, the beliefs or myths that exist about these animals and the actions taken against their bites and prevention. We used pictures of the most common species in the area to verify the vernacular names mentioned by the interviewees. Results show that the inhabitants of this region know a total of 15 species of the 20 known for the region. We were able to register ecological knowledge, vernacular names, and myths associated with snake species, among which, the 4 considered dangerous are well identified. 62% of the people surveyed kill the animal or would kill it before an encounter. We also registered the use of domestic practices to treat snake’s bites. The results of this study provide elements to generate useful tools to develop community management plans that will allow the use and conservation of snake species, focused on improving the coexistence between people and snakes.

Early Pliocene fossil snakes (Squamata, Colubroidea) with various teeth from the fissure deposit from Queshan, Henan, China

ABSTRACT Despite the world-widely reported snake fossils throughout the Cenozoic, snake fossils from China have not yet been frequently reported. Here we report a series of early Pliocene snake fossils entombed with the mammalian fauna from Houxushan, Queshan, Henan, China. By the comprehensive osteological comparison between the fossils and many extant snakes, we report three families (Colubridae, Natricidae, and Viperidae) and six genera (Cyclophiops, Elaphe, Gloydius, Lycodon, Protobothrops, and Rhabdophis) and summarised brief diagnoses of these genera. Those fossil snakes present at least three different dental types: solid teeth (regular teeth), tubular teeth, and blade-like teeth. Based on the mammalian faunas, the age of the fossil snakes can be inferred as the end of the early Pliocene near MN15 (~4.2 − 3.6 Ma). The discovery of the snake fossils emphasises the necessity of further investigating the Cenozoic snake faunas in China and provides new insights into the Cenozoic biodiversity and climate. In contrast to the cold and dry climate inferred by earlier studies, a diverse number of Oriental species and anuran-preying snakes in the Queshan herpetofauna might reveal a warmer and more humid climate in this region during the early Pliocene.

Digenea parasitizing snakes in Pampa Biome, southern Brazil

The diversity of digenetic helminths of snakes from the Pampa Biome is poorly known, with few records in Brazil, Argentina, and Uruguay. The present study documents species of Digenea parasitizing snakes in the Pampa Biome, southern Brazil. Forty-two individuals belonging to 11 species of Dipsadidae and Viperidae were examined. A total of 178 specimens belonging to 9 taxa of digenetic trematodes were found in 50% of the snakes analyzed. Habitats and host behavior may influence the parasite fauna of snakes, since helminth diversity and abundance were greater in hosts present in semi-aquatic and grassland environments. Further, 89% of digenetic trematodes use anurans as second intermediate hosts; according to the literature, anurans are the most common food resource for these snakes. In this context, studies of diet and helminth fauna of snakes are complementary and contribute to the understanding of the biology of species and their role in ecosystems.

Increasing taxon sampling suggests a complete taxonomic rearrangement in Echinantherini (Serpentes: Dipsadidae)

Although the recent advances on the relationship of its major groups, the systematics of the rich fauna of Neotropical snakes is far from being a consensus. In this sense, derived groups presenting continental distributions have represented a main challenge. The taxonomy of the snake tribe Echinantherini is one of the most contentious among the diverse family known as Dipsadidae. The tribe is poorly sampled in phylogenetic studies, resulting in conflicting hypotheses of relationships among its taxa. Moreover, several rare and micro endemic species of Echinantherini have never been evaluated within a comprehensive phylogenetic framework. Here, we assess for the first time the phylogenetic position of the rare Echinanthera amoena within Echinantherini. We based our analyses on a comprehensive multilocus dataset including 14 of the 16 species described for the tribe. Our results support the monophyly of Echinantherini and strongly indicate E. amoena as a unique lineage, phylogenetically positioned apart from all other congeners. From the three current genera (Echinanthera, Taeniophallus, and Sordellina) our results indicate that Echinanthera and Taeniophallus are paraphyletic, since the T. affinis species group is positioned as sister to Echinanthera (except E. amoena) clustering apart from the clade formed by the T. brevirostris and T. occipitalis groups. We describe new genera for the T. affinis and T. occipitalis species groups and an additional monospecific genus for E. amoena. Although we did not evaluate the phylogenetic position of T. nebularis, we described a new genus and removed it from Echinantherini since its morphology strikingly departs from all species now included in the tribe. Finally, we redefine the genera Echinanthera and Taeniophallus and we provide comments about further directions to study the biogeography and the evolution of morphological traits in Echinantherini.

A review of records of the Trimeresurus albolabris Gray, 1842 group from the Indian subcontinent: expanded description and range extension of Trimeresurus salazar, redescription of Trimeresurus septentrionalis and rediscovery of historical specimens of Trimeresurus davidi (Reptilia: Viperidae).

We revisit the identities of Trimeresurus albolabris records from India and Nepal, based on a re-examination of historically mentioned specimens. Based on morphological congruence, we identify an old specimen originally labeled as T. albolabris from Nagpur, Central Province as Trimeresurus salazar. We also provide new records of T. salazar based on molecular data from newly collected specimens in Central India. As the range of T. salazar is now known to approach that of its sister species Trimeresurus septentrionalis, we also redescribe T. septentrionalis based on the holotype and referred material. Finally, we examined two historical specimens from Madras collected during the Novara Expedition, which we identify as T. davidi, leading to a reassessment of their origin. Consequently, we remove T. albolabris from the list of Indian snake fauna.

A new tapeworm from Compsophis infralineatus (Pseudoxyrhophiidae), an endemic snake of Madagascar: Scratching the surface of undiscovered reptilian parasite diversity.

A new species of proteocephalid cestodes, provisionally assigned to the polyphyletic genus Ophiotaenia La Rue, 1911 (Cestoda: Proteocephalidae), is described from Compsophis infralineatus (Günther) (Serpentes: Pseudoxyrhophiidae) endemic to Madagascar. Ophiotaenia oreae n. sp. differs from all African and Asian species of Ophiotaenia by possessing more uterine diverticula (68-82 on one side). It is also characterised by the absence of an apical organ, the relative sizes of the cirrus-sac and ovary, the almost equatorial position of the gonopore, the diameter of the embryophore, and other biometric characteristics. Phylogenetic relationships of the new species indicate its relatedness to Indomalayan and Australasian proteocephalids from reptiles. Ophiotaenia oreae n. sp. formed a well-supported clade composed of species of Australophiotaenia de Chambrier, Beveridge and Scholz, 2018 from Australian snakes, Macrobothriotaenia ficta (Meggitt, 1931) from Xenopeltis unicolor Reinwardt in Boie from Vietnam, Ophiotaenia sp. from Trimeresurus flavomaculatus (Gray) from the Philippines, and Ophiotaenia bungari de Chambrier, Binh and Scholz, 2012 from Bungarus fasciatus (Schneider) from Vietnam. The only proteocephalid from Madagascan snakes sequenced so far, Ophiotaenia lapata Rambeloson, Ranaivoson and de Chambrier, 2012 from Madagascarophis colubrinus (Schlegel), does not form a monophyletic group with the new species. The actual species diversity of reptilian cestodes in Madagascar is undoubtedly underestimated. Because of the assumed strict (oioxenous) host specificity of reptilian proteocephalids and rich fauna of snakes occurring in Madagascar, it is plausible to expect the existence of dozens new species of proteocephalids on this island.

On the distribution of the species of the genus Hebius Thompson, 1913 (Squamata: Natricidae) in northern Thailand, including the description of a new species and a discussion on snake diversity of this region.

We examined and identified preserved specimens, skins, and photographs from a collection of 83 snakes from northern Thailand presenting the characters of the genus Hebius Thompson, 1913. They belong to at least six different taxa divided into five species including a new one described here, namely H. bitaeniatus (Wall, 1925), H. deschauenseei (Taylor, 1934), H. igneus David, Vogel, Nguyen, Orlov, Pauwels, Teyni Ziegler, 2021, Hebius khasiensis (Boulenger, 1890), and a series of specimens with strong similarities to H. khasiensis that are here preliminary identified as Hebius cf. khasiensis. Furthermore, we obtained a series of 21 different specimens in the most western strip of the region that we could not refer to any presently known species. We refer these specimens to a new species that we describe here. For each of these taxa, we provide the list of localities and specify the geographic range in northern Thailand. Lastly, we also discuss the diversity of the snake fauna of northern Thailand.

The snake fauna of the most threatened region of the Atlantic Forest: natural history, distribution, species richness and a complement to the Atlas of Brazilian Snakes

The Atlantic Forest is one of the richest tropical forests in the world, with a high endemism rate of vertebrates, including several snakes. The snake fauna of the Atlantic Forest is rich and complex, presenting differences in fauna composition along its extension. The existence of at least four endemism centers along this forest is well documented and supported by data of vertebrates, invertebrates and plants. The Pernambuco Endemism Center (PEC) is the most septentrional region of the Atlantic Forest, and it contacts areas with transitional forests and arid landscapes (Caatinga) which along with altitudinal variation enable a unique snake fauna for this region. In this study we provide: (i) an updated list of species, detailed information about natural history, as well as a detailed geographic distribution for all species recorded in the PEC; (ii) a comparison between the snake fauna of the PEC with other regions of the Atlantic Forest. The snake fauna of the PEC is composed by 86 species of 8 families. The results showed that most of the species recorded in the PEC are distributed close to the coast, probably due to the proximity of the research centers, but also due to the present distribution of the remnants close to the coast. The forest remnants in the highlands (Brejos de Altitude) harbors a high diversity of species with high similarity with the coastal forests. We found a strong separation between the snake fauna of assemblages located in southwestern and northeastern Brazil, indicating clear characteristics of the snake fauna of the PEC.

Composition and natural history of a snake community from the southern Cerrado, southeastern Brazil.

The natural history of a cerrado snake community in a protected area in southeastern Brazil (Santa Bárbara Ecological Station; SBES) is described. A visual guide and an identification key are also provided to assist researchers and local people in identifying snakes in that region.Sampling was performed through pitfall traps, time-constrained search, accidental encounters, and observations by local people for two years, which corresponded to 240 days of sampling. Among the 388 individuals found in the field, 33 snake species belonging to 21 genera of seven families were recorded. Most species were restricted or found at least once in non-forest vegetation types (campo sujo, campo cerrado, and cerrado sensu stricto) and a few were restricted to forest habitats (cerradão). Our results show that most species (1) occupy open areas; (2) present both diurnal and nocturnal activity; (3) are primarily terrestrial; (4) include lizards, mammals and/or anurans in the diet; (5) present seasonal reproductive activity; and (6) use mainly visually oriented defensive tactics. Despite its small size (3,154 ha), the SBES harbours preserved habitats and a rich and typical Cerrado snake fauna, including threatened species. Furthermore, most of the SBES snakes occur in non-forest environments (54%) and some species are sensitive to habitat disturbance.

Pinpointing Drivers of Extirpation in Sea Snakes: A Synthesis of Evidence From Ashmore Reef

Over the past decade, vertebrate populations globally have experienced significant declines in distribution and abundance. Understanding the reasons behind these population declines is the first step in implementing appropriate management responses to improve conservation outcomes. Uncovering drivers of extirpation events after the fact, however, requires a careful forensic approach to prevent similar declines elsewhere. The once abundant and species-rich sea snake fauna of Ashmore Reef Marine Park, in the Timor Sea, collapsed dramatically in the early 2000s. No such decline has occurred on surrounding reefs. We synthesise the evidence for this collapse and the subsequent slow recovery and evaluate the plausibility of potential drivers for the declines, as well as provide evidence against certain explanations that have been proposed in the past. Our systematic review shows that of seven possible hypotheses considered, at least three are credible and require additional information: (1) stochastic environmental events may have increased the snakes’ susceptibility to pathogens, (2) a resurgence in the abundance of top predators may have induced a localised change in trophic structure, and (3) an acute increase in local boat traffic may have had negative physical impacts. One or more of these factors, possibly acting in combination with as yet other unidentified factors, is the most plausible explanation for the precipitous decline in sea snake populations observed. Based on this position, we identify future research directions with a focus on addressing critical gaps in knowledge to inform and prioritise future management actions.

Crowdsourcing snake identification with online communities of professional herpetologists and avocational snake enthusiasts.

Species identification can be challenging for biologists, healthcare practitioners and members of the general public. Snakes are no exception, and the potential medical consequences of venomous snake misidentification can be significant. Here, we collected data on identification of 100 snake species by building a week-long online citizen science challenge which attracted more than 1000 participants from around the world. We show that a large community including both professional herpetologists and skilled avocational snake enthusiasts with the potential to quickly (less than 2 min) and accurately (69–90%; see text) identify snakes is active online around the clock, but that only a small fraction of community members are proficient at identifying snakes to the species level, even when provided with the snake's geographical origin. Nevertheless, participants showed great enthusiasm and engagement, and our study provides evidence that innovative citizen science/crowdsourcing approaches can play significant roles in training and building capacity. Although identification by an expert familiar with the local snake fauna will always be the gold standard, we suggest that healthcare workers, clinicians, epidemiologists and other parties interested in snakebite could become more connected to these communities, and that professional herpetologists and skilled avocational snake enthusiasts could organize ways to help connect medical professionals to crowdsourcing platforms. Involving skilled avocational snake enthusiasts in decision making could build the capacity of healthcare workers to identify snakes more quickly, specifically and accurately, and ultimately improve snakebite treatment data and outcomes.

Species richness and distribution patterns of the snake fauna of Rio Grande do Norte state, northeastern Brazil.

The Neotropics are one of the richest regions in biodiversity globally. Still, much remains unknown about the mechanisms and processes responsible for the accumulation of species in this region. Among the many limitations on our current knowledge on the region's biodiversity, understanding of community composition and species distributions is limited and greatly biased in many Brazilian regions. We present information on species composition, habitat use, geographic distribution, taxonomic accounts, and conservation of snakes from Rio Grande do Norte state, Northeastern Brazil. We compiled, from primary and literature data, 851 snake records from seven families and 47 species, with five new records for the state. Species are mainly terrestrial and semi-arboreal and associated with at least six vegetation types from Caatinga and Atlantic Forest domains. None of the species is listed in threatened categories of IUCN, while two species are listed in the Brazilian Threatened Fauna list. Our data covers 32.34% of the state's area, a consequence of locally limited inventories and lack of long-term studies on snakes' fauna. The richest areas within the state are near large cities, which lack protected areas for the species they harbor, and highlights the necessity of protective policies and conservation actions.

Vicariance and regionalization patterns in snakes of the South American Atlantic Forest megadiverse hotspot

AbstractAimVicariance has often been invoked to explain bioregionalization patterns in the Neotropics. Using a revised point locality data for endemic species, we aimed to test for the first time the predictions of the vicariance model in shaping biogeographical regions for endemic snakes in the Atlantic Forest (AF) megadiverse hotspot.LocationSouth American Atlantic Forest.TaxonSnakes (Reptilia, Serpentes).MethodsTo identify the non‐random groups of co‐distributed species, we mapped 21,101 point locality records in a grid cell of 0.5° × 0.5° across the AF, and constructed a presence–absence matrix of endemic species. The two major predictions of vicariance model were tested by Biotic Elements (BE) analysis, searching for groups of significantly co‐distributed species (Biotic Elements) by comparing distances between observed and artificial random ranges, produced under null models from Monte Carlo simulations. We also tested for the occurrence of sister species in different Biotic Elements, and compared our results with previous bioregionalization schemes revealed by other organisms in the AF.ResultsWe recorded 252 species of snakes in the Atlantic Forest, of which 79 (31%) are endemic to this domain. Biotic Elements analysis with endemic species revealed seven clusters of co‐distributed species (BEs) corresponding to biogeographical regions. The significant non‐random clusters of geographical ranges revealed in BE analysis, and the distribution of sister species in different BEs, validated both central predictions of the vicariance model.Main conclusionsSnakes defined non‐random biogeographical regions in the Atlantic Forest, and these were congruent with previously identified areas based on other groups of organisms, indicating that general processes influenced geographical ranges across the region. Both central predictions of the vicariance model were valid, indicating that vicariant events must have been important in shaping non‐random clusters of co‐distributed snakes in this biodiversity hotspot, harbouring some of the richest snake faunas on the planet.