Snake Genus Research Articles

POTENTIAL GEOGRAPHIC DISTRIBUTION OF THE GENUS Micrurus WAGLER, 1824 (SERPENTES: ELAPIDAE) AND ANTIVENOM SUPPLY IN RIO DE JANEIRO STATE, BRAZIL

The coral snake genus Micrurus has non-aggressive behavior, being responsible for only 0.4% of the reports of snakebites in Brazil. However, although rare, accidents are potentially serious due to rapidly evolving respiratory paralysis. In the last few years, there was an abrupt reduction in the number of hospitals receiving antivenom support in Rio de Janeiro State, and currently the Health Ministry of Brazil distributes the antivenom only to 25 hospitals in 21 municipalities, even so with no data on specific serum provided by each hospital. This study aimed to determine the potential distribution of Micrurus species in Rio de Janeiro State in order to compare potential areas for risk of elapidic accidents with the localities assisted by hospitals with antivenom distribution. We performed ecological niche models to generate maps of potential distribution for all species through several niche algorithms. Based on these results we analyzed and discussed the consequences of this change in the number of hospitals receiving antivenom. Our results revealed the potential occurrence of the genus throughout the State territory and show a partially homogeneous distribution of health units, although the northern region represents an area with a deficiency in hospital coverage. According to our results and data from the Rio de Janeiro State Secretary of Health, it is highly desirable that at least some antivenom service centers in the regions “Metropolitana” and “Baixadas Litorâneas” receive antielapidic serum and that there be an increase in the number of units in “Norte Fluminense” and “Noroeste Fluminense” regions of Rio de Janeiro State.

Venomous Landmines: Clinical Implications of Extreme Coagulotoxic Diversification and Differential Neutralization by Antivenom of Venoms within the Viperid Snake Genus Bitis.

The genus Bitis comprises 17 snake species that inhabit Africa and the Arabian Peninsula. They are responsible for a significant proportion of snakebites in the region. The venoms of the two independent lineages of giant Bitis (B. arietans and again in the common ancestor of the clade consisting of B. gabonica, B. nasicornis, B. parviocula and B. rhinoceros) induce an array of debilitating effects including anticoagulation, hemorrhagic shock and cytotoxicity, whilst the dwarf species B. atropos is known to have strong neurotoxic effects. However, the venom effects of the other species within the genus have not been explored in detail. A series of coagulation assays were implemented to assess the coagulotoxic venom effects of fourteen species within the genus. This study identified procoagulant venom as the ancestral condition, retained only by the basal dwarf species B. worthingtoni, suggesting anticoagulant venom is a derived trait within the Bitis genus and has been secondarily amplified on at least four occasions. A wide range of anticoagulant mechanisms were identified, such as coagulant and destructive activities upon fibrinogen in both giant and dwarf Bitis and the action of inhibiting the prothrombinase complex, which is present in a clade of dwarf Bitis. Antivenom studies revealed that while the procoagulant effects of B. worthingtoni were poorly neutralized, and thus a cause for concern, the differential mechanisms of anticoagulation in other species were all well neutralized. Thus, this study concludes there is a wide range of coagulotoxic mechanisms which have evolved within the Bitis genus and that clinical management strategies are limited for the procoagulant effects of B. worthingtoni, but that anticoagulant effects of other species are readily treated by the South African polyvalent antivenom. These results therefore have direct, real-work implications for the treatment of envenomed patients.

A new member of the genus Sinonatrix (Serpentes: Colubridae) from western China.

A new member of the natricine snake genus Sinonatrix Rossman Eberle, 1977 is described from Yunnan Province, southwestern China, based on a single female specimen. The new species, Sinonatrix yapingi sp. nov., is distinguished from its congeners and related species by the following combination of characters: 1) large body size (maximum total length more than 795 mm); 2) dorsal scales in 19-19-17 rows, moderately keeled except outer four; 3) prefrontal single; 4) ventral scales 149, subcaudals 55, paired; 5) cloaca divided; 6) body bands 30; 7) belly milk-white, without speckles or bands; 8) reduction of dorsal scale rows from 19 to 17 anterior to 90th ventral scale; 9) reduction of caudodorsal scale rows from 8 to 6 anterior to 12th subcaudal and from 6 to 4 anterior to 38th subcaudal; 10) postorbital bones not in contact with frontals, with weak parietal ridge; end of supratemporal bones extending beyond braincase; maxillary teeth 25, last two not enlarged; and, dentary teeth 26. In addition, the genetic distances between the new species and other representatives of Sinonatrix ranged from 14.6% to 15.0%.

Rediscovery of the rare Andean blindsnake Anomalepis colombia Marx 1953(Serpentes: Anomalepididae) in the wild.

The fossorial snake genus Anomalepis Jan 1860 currently comprises four species with distribution restricted to the Neotropics, occurring from Nicaragua to trans-Andean Peru. Species of Anomalepis occur on the mainland from sea level to about 2,700 m elevation in habitats that range from xerophyte vegetation to tropical wet forests (Kofron 1988; McDiarmid et al. 1999; Uetz et al. 2019; Wallach et al. 2014). Kofron (1988) performed a taxonomic review of the genus Anomalepis, recognizing two phenotypic clusters of species: the A. mexicanus Jan 1860 composed exclusively by its nominal form, and the A. aspinosus Taylor 1939 group consisting of the former species, A. colombia Marx 1953 (Fig. 1) and A. flavapices Peters 1957. While Anomalepis aspinosus occurs in xerophytic formation from 500-2700 above sea level (asl hereafter) along the Peruvian Andes (Kofron 1988; McDiarmid et al. 1999; Wallach et al. 2014), and Anomalepis flavapices is found in the coastal rainforest plains of northwestern Ecuador (Kofron 1988; Wallach et al. 2014), Anomalepis mexicanus presents the most widespread distribution amongst its congeners, occurring in northeastern Honduras, Nicaragua, Costa Rica and Panama from sea level to 725 m altitude. Even though this species has previously been recorded for Peru (Kofron, 1988), it seems unlikely that this specimen belongs to A. mexicanus due to its distinct meristic features (see Kofron 1988) and its outlandish record (see Fig. 2). Marx (1953) described Anomalepis colombia based on a single specimen collected in 1946 by Kjell von Sneidern at La Selva (05º25'23N, 74º57'44W; 1700 m asl), municipality of Pueblo Rico, department of Caldas, Colombia. As far as we know, since its original description, no additional specimen of A. colombia has been reported in literature (cf. Kofron 1988; McDiarmid et al. 1999; Wallach et al. 2014).

Ancient habitat shifts and organismal diversification are decoupled in the African viper genus Bitis (Serpentes: Viperidae)

AbstractAimThe expansion of open habitats during the mid‐Miocene has been hypothesized as a driver of allopatric speciation for many African taxa. This habitat‐dependent mode of diversification has been implicated in the shift from C3 (e.g. forest/woodland) to C4 dominated systems (i.e. open savanna, grasslands) in a number of African squamates. We examined this hypothesis using a genus of African viperid snakes (Bitis) with both open habitat and forest‐dwelling representatives.LocationAfrica.MethodsA comprehensive multilocus dataset was used to generate a calibrated species tree using a multispecies coalescent model. Individual gene trees and patterns of nuclear allele sharing were used to assess species monophyly and isolation. To test the habitat‐dependent evolution hypothesis, we generated an ancestral character state reconstruction for open and closed habitats using the dated phylogeny. This was related to the timing of open habitat expansion and forest/woodland contraction in Africa.ResultsThe genus Bitis originated in the Oligocene, with species level diversification in the late Miocene/Pliocene. Four well‐supported clades correspond to the recognized subgenera Bitis, Keniabitis, Macrocerastes and Calechidna. Several previously unrecognized lineages potentially represent cryptic species.Main conclusionsHabitat‐dependent evolution does not appear to have been a main driver for generic level viperine diversification: the ancestral state for Bitis was open habitat and at least one clade moved into forest in the Miocene, long after forest had contracted and fragmented. Forest‐dependent species diversified only in the late Miocene, presumably as forest became further reduced in extent, fitting an allopatric model of speciation. Although our results do not favour a general pattern of habitat‐dependent diversification in Bitis, cladogenesis within the subgenus Calechidna for “arenicolous” species (Bitis caudalis complex) and “rupicolous” species (B. atropos‐cornuta complex), corresponds to the aridification of southwest Africa. This suggests there are subtleties not captured in the broad open habitat category, which are relevant for understanding the role of habitat‐dependent evolution.

Large-scale molecular phylogeny, morphology, divergence-time estimation, and the fossil record of advanced caenophidian snakes (Squamata: Serpentes).

Caenophidian snakes include the file snake genus Acrochordus and advanced colubroidean snakes that radiated mainly during the Neogene. Although caenophidian snakes are a well-supported clade, their inferred affinities, based either on molecular or morphological data, remain poorly known or controversial. Here, we provide an expanded molecular phylogenetic analysis of Caenophidia and use three non-parametric measures of support–Shimodaira-Hasegawa-Like test (SHL), Felsentein (FBP) and transfer (TBE) bootstrap measures–to evaluate the robustness of each clade in the molecular tree. That very different alternative support values are common suggests that results based on only one support value should be viewed with caution. Using a scheme to combine support values, we find 20.9% of the 1265 clades comprising the inferred caenophidian tree are unambiguously supported by both SHL and FBP values, while almost 37% are unsupported or ambiguously supported, revealing the substantial extent of phylogenetic problems within Caenophidia. Combined FBP/TBE support values show similar results, while SHL/TBE result in slightly higher combined values. We consider key morphological attributes of colubroidean cranial, vertebral and hemipenial anatomy and provide additional morphological evidence supporting the clades Colubroides, Colubriformes, and Endoglyptodonta. We review and revise the relevant caenophidian fossil record and provide a time-calibrated tree derived from our molecular data to discuss the main cladogenetic events that resulted in present-day patterns of caenophidian diversification. Our results suggest that all extant families of Colubroidea and Elapoidea composing the present-day endoglyptodont fauna originated rapidly within the early Oligocene–between approximately 33 and 28 Mya–following the major terrestrial faunal turnover known as the “Grande Coupure” and associated with the overall climate shift at the Eocene-Oligocene boundary. Our results further suggest that the caenophidian radiation originated within the Caenozoic, with the divergence between Colubroides and Acrochordidae occurring in the early Eocene, at ~ 56 Mya.

A new genus and species of natricine snake from northeast India.

Based on the first molecular phylogenetic analyses of samples from northeast India, specimens referred to Rhabdops from this region are more closely related to the southeast and east Asian natricine genera Opisthotropis Günther, 1872 and Sinonatrix Rossman Eberle, 1977 (as well as to New World and western Palearctic natricines) than to peninsular Indian (true) Rhabdops. Morphologically, these northeast Indian populations differ from other natricines by having a single ('fused' or unpaired) internasal shield and a single prefrontal shield. Given the morphological and phylogenetic distinctiveness of these northeast Indian populations, we refer them to a new genus, Smithophis gen. nov., and transfer Rhabdops bicolor (Blyth, 1854) to Smithophis bicolor comb. nov. Based on morphological and molecular variation within our northeast Indian sample, we additionally describe Smithophis atemporalis sp. nov. from the state of Mizoram.

New Polychromatic Species of Atractus (Serpentes: Dipsadidae) from the Eastern Portion of the Colombian Andes

We describe herein a new polychromatic species of the snake genus Atractus from the cloud forests of the northeastern Andes of Colombia. The new species is distinguished from all congeners by having an exclusive combination of phenotypic characters, such as: dorsal scale rows 17, loreal long, seven to ten maxillary teeth, ventrals 156–174 in females and 153–169 in males, subcaudals 20–30 in females and 23–30 in males, dorsum with variable coloration, changing from dark green to orange or red with a black nuchal band (three to four scales long) connected to a black vertebral line and two black dorsolateral continuous stripes from the occipital region to tip of the tail, venter with irregular black blotches, relatively small body size, small tail length in females and moderately long in males, hemipenis moderately bilobed, semicapitate and semicalyculate. We compared the new species with all congeners occurring along the Cordillera Oriental in Colombia, Sierra de Perija in the Colombia/Venezuela frontier and Cordillera de Merida in Venezuela. We discussed aspects related to polychromatism and its implication toward a robust taxonomy for the genus Atractus.Describimos una nueva especie de serpiente policromatica del genero Atractus para los bosques nublados del noreste de los Andes de Colombia. La nueva especie se distingue de todos los congeneres por tener una combinacion exclusiva de caracteres fenotipicos, como: escamas dorsales en 17 hileras, loreales largas, siete a diez dientes maxilares, ventrales 156–174 en hembras y 153–169 en machos, subcaudales 20–30 en hembras y 23–30 en machos, dorso con coloracion variable, cambiando de verde oscuro a naranja o rojo con una banda nucal negra (largo de tres o cuatro escamas) conectada a una linea vertebral negra y dos franjas continuas dorsolaterales negras desde la region occipital hasta la punta de la cola, superficie ventral del cuerpo con manchas irregulares negras, tamano corporal relativamente pequeno, longitud de la cola pequena en las hembras y moderadamente larga en los machos, hemipene moderadamente bilobado, semicapitado y semicaliculado. Comparamos las nuevas especies con todos los congeneres que ocurren a lo largo de la Cordillera Oriental en Colombia, Sierra de Perija en la frontera de Colombia/Venezuela y la Cordillera de Merida en Venezuela. Discutimos aspectos relacionados con el policromatismo y su implicacion hacia una taxonomia solida para el genero Atractus.

Three new species of the snake genus Achalinus from Vietnam (Squamata: Xenodermatidae).

Three new species of the xenodermatid genus Achalinus are described from northern Vietnam based on morphological and molecular evidence: Achalinus juliani sp. nov. is characterized by a combination of the following characters: 1) maxillary teeth 28; 2) suture between the internasals distinctly longer than that between the prefrontals; 3) internasal not fused to prefrontal; 4) loreal not fused with prefrontal; 5) infralabials 6; 6) mental separated from anterior chin shields; 7) two elongated anterior temporals, in contact with the eye, and two posterior temporals; 8) dorsal scales in 25-23-23 rows, keeled; 9) ventrals 173-179; 10) subcaudals 77-91, unpaired; 11) a total length of at least 413 mm (with a maximum tail length of 109 mm, and a tail/total length ratio of 0.22-0.37); 12) dorsum in preservative reddish to greyish brown above, with the lower and posterior head sides being paler; venter greyish cream, with the underside of the tail being somewhat darker. Achalinus timi sp. nov. is characterized by a combination of the following characters: 1) maxillary teeth 27; 2) suture between the internasals distinctly longer than that between the prefrontals; 3) loreal fused with the prefrontal on each side, with the prefrontal extending towards the supralabials; 4) dorsal scales in 25-25-23 rows, keeled; 5) ventrals 170+1; 6) subcaudals 72, unpaired; 7) a total length of at least 177.9 mm in males (with a tail length of 37.9 mm, and a tail/total length ratio of 0.21); 8) dorsum in preservative reddish to greyish brown above, with wide portion of the vertebral region being distinctly darker; the lower head sides somewhat paler; infralabial and chin shields light greyish brown; venter greyish cream, with the underside of the tail being somewhat darker and the chin region somewhat paler. Achalinus emilyae sp. nov. is characterized by a combination of the following characters: 1) maxillary teeth 27 or 28; 2) suture between internasals distinctly longer than that between the prefrontals; 3) internasal not fused to prefrontal; 4) loreal not fused with prefrontal; 5) infralabials 5; 6) mental separated from anterior chin shields; 7) two anterior temporals, only the upper one in contact with eye, and two posterior temporals; 8) dorsal scales in 23-23-23 rows, keeled; 9) ventrals in females 157-161; 10) subcaudals in females 63, unpaired; 11) a total length of at least 519.5 mm (with a maximum tail length of 95.1 mm, and a tail/total length ratio of 0.18 in females); 12) dorsum iridescent pale yellowish brown with a dark longitudinal mid-dorsal stripe. In terms of pairwise genetic distance (cytochrome c oxidase subunit 1, COI), the three new species differ by at least 12.7% from other members of the genus, including themselves. The total number of Achalinus known is increased to twelve and the number of Achalinus species known from Vietnam is increased from three to six. Currently ten species of xenodermatids are known to exist in Vietnam: Achalinus ater, A. emilyae, A. juliani, A. rufescens, A. spinalis, A. timi, Fimbrios klossi, F. smithi, Parafimbrios lao, and P. vietnamensis.

Taxonomic status of Apostolepisbarrioi Lema, 1978, with comments on the taxonomic instability of Apostolepis Cope, 1862 (Serpentes, Dipsadidae).

Apostolepis is a diverse neotropical snake genus, which has been historically subjected to poor taxonomic descriptions, largely based on either a small type series or subjective diagnoses. We evaluate the case of Apostolepisbarrioi Lema, 1978 and its intricate taxonomic history, suggesting its synonymization with Apostolepisdimidiata (Jan, 1862), and providing brief commentary on the taxonomic instability that has been plaguing the genus.

Systematic review of Atractus schach (Serpentes: Dipsadidae) species complex from the Guiana Shield with description of three new species

The Guiana Shield harbours one of the best preserved and largest extents of tropical forest on Earth and an immense biodiversity. The herpetofauna of this region remains poorly known. The species-rich snake genus Atractus contains ∼140 species, many with complicated taxonomic histories, including A. schach. Examination of specimens in museums and newly collected material from French Guiana has allowed the illustration of hemipenial morphology for the first time and an expanded diagnosis. Concatenated molecular phylogenetic (mitochondrial and nuclear genes) and phenotypic (morphometrics, external and hemipenial morphology) analyses confirm non-monophyly of the A. flammigerus group and indicate that A. schach is a species complex with three new species described here. The geographic distribution of A. schach sensu stricto is restricted to Guiana, Surinam, and French Guiana north of Tumucumaque massif. Populations tentatively assigned to A. schach from the east from French Guiana in the Roura lowlands to Almeirim, and from central Amazonia between the Negro and Trombetas rivers in Brazil are also recognized as new species. Our results suggest that populations from south of the Amazon River are not conspecific with those from the Guiana Shield.http://www.zoobank.org/urn:lsid:zoobank.org:pub:A7AE40BC-4716-4302-B3BE-1F43600B0A72

New insights into the phylogeographic distribution of the 3FTx/PLA2 venom dichotomy across genus Micrurus in South America

Micrurus is a monophyletic genus of venomous coral snakes of the family Elapidae. The ~80 recognized species within this genus are endemic to the Americas, and are distributed from southeastern United States to northern Argentina. Although relatively few bites are recorded due to their reclusive nature, semi-fossorial habits, and their occurrence in sparsely populated areas, coral snakes possess powerful venoms that target the cholinergic system and, if early treatment is missed, can cause neuromuscular paralysis, respiratory failure, and death by asphyxiation within hours of envenoming. The to-date proteomically characterized 18 micrurine venoms exhibit a puzzling phenotypic dichotomy, characterized by the toxin arsenal being dominated either by pre-synaptically acting PLA2s or post-synaptic 3FTxs, and a general, but imperfect, distributional pattern of these venom phenotypes along the North-South axis of the American continent. The lack of perfect phylogenetic clustering suggests that phylogeny may not be the sole factor driving the evolution of the divergent venom phenotypes across Micrurus venoms. To shed new light on the origin and expression pattern of the 3FTx/PLA2 venom dichotomy, we have conducted a comparative proteomics analysis of venoms from the Brazilian ribbon coral snake, Micrurus lemniscatus carvalhoi, sourced from different localities in the Brazilian states of São Paulo; the Caatinga coral snake, M. ibiboboca, from central Bahia state (Brazil); two Micrurus specimens of uncertain taxonomy collected in the Brazilian states of Alagoas and Rio de Janeiro; and the Western ribbon coral snake, M. l. helleri, from Leticia, the southernmost town of the Colombian Department of Amazonas. Venoms from São Paulo and Rio de Janeiro showed 3FTx-predominant phenotypes, while in venoms from Leticia, Alagoas and Bahia PLA2s represented the major toxin family. Comparative venom proteomics suggests that both Micrurus venom phenotypes exhibit a high degree of toxin evolvability. Mapping the 3FTx/PLA2 dichotomy across the Americas points to a phylogeographic pattern for venom phenotypes consistent with, but more complex than, the North-South distribution hypothesis anticipated in previous investigations. BIOLOGICAL SIGNIFICANCE: New World coral snakes (Micrurus: Elapidae) produce potent venoms that target pre- and post-synaptically cholinergic nerve terminals resulting in neuromuscular paralysis, and in severe envenomings, may lead to death from asphyxiation by respiratory arrest. Presynaptic β-neurotoxins of group IA PLA2 protein subfamily and postsynaptic α-neurotoxins with 3FTx fold are the major components (>80%) of coral snake venoms. Micrurine venoms exhibit a puzzling phenotypic venom dichotomy, characterized by the dominant expression of either α- or β-neurotoxins. The distribution of these alternative compositional profiles has been fragmentarily studied both across Micrurus phylogeny and along the North-South axis of the genus radiation in the American continent, from southern United States to Northern Argentina. The unpredictability of the neurotoxin profile across the distribution range of the coral snakes represents a difficulty for applying the most appropriate treatment upon a coral snakebite. A deep knowledge of the phylogeographic distribution and the evolution of dichotomic Micrurus venoms would be useful for tracing the evolutionary path to their present day phenotypes, rationalizing the patchy cross-reactivity of current Micrurus antivenoms, and improving the efficacy of antivenoms to neutralize coral snake envenomings.

Might Dendrelaphis caudolineatus (Gray, 1834) (Squamata: Colubridae) present in India?

The colubrid snake genus Dendrelaphis comprises of 45 species (Uetz et al. 2018) of which eleven currently occurs in India (Aengals et al. 2018). A member of this genus, Dendrelaphis caudolineatus (Gray, 1834), was once considered a wide-ranging species in Southeast Asia, the Philippines and the Indo-Australian Archipelago, until Van Rooijen Vogel (2012) resolved taxonomy of this species complex. Now its range is restricted from southern Thailand to Sundaland (Peninsular Malaysia, Sumatra, Billiton and Borneo; presence doubtful in Java of Indonesia) (Van Rooijen Vogel 2012).

A new species of the snake genus Hebius Thompson from Northeast India(Squamata: Natricidae).

A new species of the family Natricidae Bonaparte is described from a single specimen obtained in Arunachal State, northeastern India. On the basis of its external morphology and of its dentition on the upper maxilla, i.e. 24 + 3 distinctly enlarged teeth separated by a short diastema, it is referred to the genus Hebius Thompson. Hebius lacrima spec. nov. is distinguished from other species of the genera Hebius, Amphiesma Duméril, Bibron Duméril and Herpetoreas Günther, by the combination of an elongate body, 19 dorsal scale rows at midbody, a distinctive broad, white band on the supralabials interrupted by a dark blotch below the eye, absence of dorsolateral stripes replaced by series of transversally elliptical or divided dorsolateral spots, a cream venter with lateral dark blotches, and scales of the first dorsal scale row entirely smooth. The interrupted, broad, lateral stripe of the head differentiates Hebius lacrima spec. nov. from all other species of the genera Hebius and Herpetoreas inhabiting the Indo-Himalayan and Indochinese Regions. This new species is compared in detail with other Asian species of Natricidae having 19 dorsal scale rows.

On the second specimen of Atractus alytogrammus (Serpentes: Dipsadidae), with description of its unusual hemipenial morphology.

The semi-fossorial snakes of the genus Atractus Wagler 1828 are widely distributed throughout South America, ranging from Panama to northeastern Argentina at elevations from sea level to 4500 m (Passos et al. 2013a). Atractus currently comprises 150 species that inhabiting several types of tropical habitats, being the most diverse genus of snakes in the world (Passos et al. 2018). Colombia harbours the most species richness of the genus with about 42 currently recognized species, representing about 1/3 of generic diversity (Uetz et al. 2018). Köhler Kieckbusch (2014) recently has named Atractus alytogrammus based on an individual collected by Federico Meden more than fifty years ago near the municipality of San José de Guaviare (2°33'55''N, 72°38'19''W). The second known specimen of A. alytogrammus was found by A.F. Aponte (male, ICN-R-13018) hidden under a pile of palm leaves (3°00'05"N, 72°13'9.9"W; 209 m above sea level) at 7:58 am on February 02 2016 in the oil palm plantations of POLIGROW Colombia Ltda, municipality of Mapiripán, department of Meta, Colombia. This region is located in the Orinoquia-Amazonia ecotone 82 Km (airline) northeast from the type-locality (Fig. 1). I report herein the unknown color in life (Fig. 2), change of shades after preservation (Fig. 3B-D) and hemipenial morphology (Fig. 4), besides amplifying the meristic and morphometric variability of this poorly known species (Table 1).

The complete mitochondrial genome of the tartar Sand Boa Eryx tataricus

Eryx is a genus of snakes belonging to the family Boidae. In this study, the mitochondrial genome sequence of Eryx tataricus was generated using a PacBio RSII DNA sequencer employing the single molecule, real-time sequencing technology. A maximum-likelihood (ML) phylogenetic tree of 26 snakes was re-constructed based on the 13 protein-coding genes for convincing the mitochondrial DNA sequences.

The mitochondrial genome of the bamboo false cobra (Pseudoxenodon bambusicola)

Pseudoxenodon is a genus of snakes belonging to the family Colubridae. In this study, the mitochondrial genome sequence of Pseudoxenodon bambusicola was generated through the next-generation sequencing technique. A bayesian inference (BI) phylogenetic tree based on the 12 protein-coding genes was re-constructed for convincing the mitochondrial DNA sequences.

A new species of Parafimbrios from northern Vietnam (Squamata: Xenodermatidae).

A second species of the previously monotypic snake genus Parafimbrios is described from Lai Chau Province, northern Vietnam, based both on molecular and morphological evidences. Parafimbrios vietnamensis sp. nov. is characterized by a combination of the following characters: 1) rostral laterally with two raised, curved edges; the upper one, together with a horizontal curved ridge of tissue, separate the rostral from the internasals; 2) nasal in contact zone with rostral with curved raised edge; 3) nasal in contact zone with supralabials each with two small oblique, curved raised edges located above first and second as well as above second and third supralabials; 4) suture between the internasals much longer than that between the prefrontals; 5) supralabials 8, with the first four bearing raised edges; 6) infralabials 7; mental and anterior three to four infralabials with raised edges; 7) temporals 4+4-5; 8) 35-33-29 dorsal scale rows; 9) laterally rounded ventrals 164; 10) unpaired subcaudals 49; 11) total length of at least 266 mm in males (with a tail length of 44 mm, and a tail / total length ratio of 0. 165). This discovery brings the total number of taxa of the family Xenodermatidae in Vietnam to seven species: Achalinus ater, A. rufescens, A. spinalis, Fimbrios klossi, F. smithi, Parafimbrios lao, and P. vietnamensis.

Caudals and Calyces: The Curious Case of a Consumed Chiapan Colubroid

Abstract A new genus and species of colubroid snake is described from the isolated highlands of western Chiapas. This enigmatic little snake possesses a unique suite of characters that defies placi...

Mud in the blood: Novel potent anticoagulant coagulotoxicity in the venoms of the Australian elapid snake genus Denisonia (mud adders) and relative antivenom efficacy

Due to their potent coagulotoxicity, Australian elapid venoms are unique relative to non-Australian members of the Elapidae snake family. The majority of Australian elapids possess potent procoagulant venom, while only a few species have been identified as possessing anticoagulant venoms. The majority of research to-date has concentrated on large species with range distributions overlapping major city centres, such as brown snakes (Pseudonaja spp.) and taipans (Oxyuranus spp.). We investigated the venom from the poorly studied genus Denisonia and documented anticoagulant activities that were differentially potent on amphibian, avian, and human plasmas. Both species were potently anticoagulant upon amphibian plasma, consistent with these snakes preying upon frogs as their primary food source. While D. devisi was only relatively weakly active on avian and human plasma, D. maculata was potently anticoagulant to amphibian, avian, and human plasma. The mechanism of anticoagulant action was determined to be the inhibition of prothrombin activation by Factor Xa by blocking the formation of the prothrombinase complex. Fractionation of D. maculata venom followed by MS sequencing revealed that the toxins responsible were Group I phospholipase A2. As no antivenom is produced for this species or its near relatives, we examined the ability of Seqirus Australian snake polyvalent antivenom to neutralise the anticoagulant effects, with this antivenom shown to be effective. These results contribute to the body of knowledge regarding adaptive evolution of venom, revealing a unique taxon-specific anticoagulant effect for D. devisi venom. These results also reveal the potential effects and mechanisms behind envenomation by the potently acting D. maculata venom on human plasma, while the discovery of the efficacy of an available antivenom provides information crucial to the design of snakebite management strategies.