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... Most coralsnakes have a color pattern of some combination of red, yellow or white, and black rings (Campbell and Lamar, 2004). Although a comprehensive phylogenetic analysis of the species that make up the genus is still pending (Zaher et al., 2021), some monophyletic groups have been identified based on the structure of their hemipenes and molecular characters: the group of monadal black ring coralsnakes, which have slender and strongly bifurcated hemipenes; the group of triad pattern coralsnakes with short, bilobed hemipenes; and the group of bicolored coralsnakes with strongly bilobed and slender hemipenes (Slowinski, 1995). Envenomings by coralsnakes are characterized by paresthesia, local pain, palpebral ptosis, dizziness, blurred vision, weakness, slight local edema, erythema, dysphagia, dyspnea, myalgia, salivation and respiratory failure which may lead to death (Bucaretchi et al., 2016). ...
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Coralsnakes belong to the family Elapidae and possess venoms which are lethal to humans and can be grouped based on the predominance of either three finger toxins (3FTxs) or phospholipases A2 (PLA2s). A proteomic and toxicological analysis of the venom of the coralsnake Micrurus yatesi was performed. This species, distributed in southeastern Costa Rica, was formerly considered a subspecies of M. alleni. Results showed that this venom is PLA2-rich, in contrast with the previously studied venom of Micrurus alleni. Toxicological evaluation of the venom, in accordance with proteomic data, revealed that it has a markedly higher in vitro PLA2 activity upon a synthetic substrate than M. alleni. The evaluation of in vivo myotoxicity in CD-1 mice using histological evaluation and plasma creatine kinase release also showed that M. yatesi venom caused muscle damage. A commercial equine antivenom prepared using the venom of Micrurus nigrocinctus displayed a similar recognition of the venoms of M. yatesi and M. nigrocinctus by enzyme immunoassay. This antivenom also immunorecognized the main fractions of the venom of M. yatesi and was able to neutralize its lethal effect in a murine model.
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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 phyloge-netic analysis of Caenophidia and use three non-parametric measures of support-Shimo-daira-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 PLOS ONE | https://doi.
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Çalta (Pliocène supérieur d'Anatolie) est le premier gisement ayant livré des Batraciens et Reptiles cénozoïques dans les régions méditerranéennes orientales ; de nombreuses familles sont représentées. Ce gisement représente un jalon important pour l'histoire des Squamates périméditerranéens car, les éléments paléarctiques de la faune de Squamates du Maghreb ayant pénétré en Afrique par la partie orientale du bassin méditerranéen, l'Anatolie se trouve sur la voie de passage de ces faunes en direction de l'Afrique. Les Squamates de Çalta, comme ceux du Néogène marocain, suggèrent que la pénétration des éléments eurasiatiques en Afrique a été progressive et ne s'est achevée que récemment.
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We present new molecular data (mtDNA sequences and allozymes) for several species of South American "triad" coral snakes. We present a phylogenetic hypothesis for the group based on analysis of molecular characters using both maximum parsimony (MP) and maximum likelihood (ML) optimality criteria. Results from both methods are generally congruent and suggest a basal position for the morphologically and ecologically unique Micrurus surinamensis. The M. frontalis complex is shown to be paraphyletic with respect to several other species in the parsimony and likelihood trees, but a topology constraining this group to monophyly cannot be statistically rejected compared to the best MP or ML trees. All analyses provide strong support for polyphyly of M. "lemniscatus" and in this case, the alternative monophyly topology is strongly rejected under both optimality criteria. These results underscore the need for a more detailed analysis of populations currently assigned to M. lemniscatus.
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The early Eocene of Panandhro Mine (northwestern India) has produced a rich snake fauna largely dominated by palaeophiids. Three families are present: Palaeophiidae,? Madtsoiidae or Boidae, and an indeterminate family of Colubroidea. The Palaeophiidae include two species: Pterosphenus kutchensis n. sp., that shows peculiar features, and Pt. biswasi n. sp. They are the earliest representatives of the genus. Madtsoiidae or Boidae are represented by only two specimens that do not permit distinction between these two families. If these fossils belong to the Boidae, then they might be the earliest representatives of that family in Asia. The colubroid from this site ranks among the earliest Cenozoic representatives of the group. The possibility that it belongs to the Colubridae cannot be excluded; if this is the case, it would be the earliest known colubrid. Nearly all specimens belong to Pterosphenus Lucas, 1899 that was a highly aquatic genus. It lived in shallow water, probably in marine environment close to the coasts and/or in freshwater. © Publications Scientifiques du Muséum national d'Histoire naturelle, Paris.
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We performed phylogenetic analyses of the Asian coral snakes (Elapidae: Calliophis and Maticora) based on morphological and cytochrome b sequence characters, comparing them also to American coral snakes (Micruroides and Micrurus). Asian coral snakes fall into three major clades: (1) the tropical mainland species C. beddomei, C. bibroni, C. gracilis, C. maculiceps, C. melanurus, C. nigrescens, and Maticora, (2) the Philippine C. calligaster, and (3) the northern tropical/subtropical mainland species C. hatori, C. japonicus, C. kelloggi, C. macclellandi, and C. sauteri. This last clade is closely related to the New World coral snakes. These three clades of Asian coral snakes warrant generic recognition, which necessitates a new name for the last clade. The pattern of relationships inferred in this study imply that the New World coral snakes are derived from an ancestor which dispersed from Asia into the New World, presumably over the Bering land bridge.
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Snakes of the World: A Catalogue of Living and Extinct Species-the first catalogue of its kind-covers all living and fossil snakes described between 1758 and 2012, comprising 3,509 living and 274 extinct species allocated to 539 living and 112 extinct genera. Also included are 54 genera and 302 species that are dubious or invalid, resulting in recognition of 705 genera and 4,085 species. Features: • Alphabetical listings by genus and species • Individual accounts for each genus and species • Detailed data on type specimens and type localities • All subspecies, synonyms, and proposed snake names • Distribution of species by country, province, and elevation • Distribution of fossils by country and geological periods • Major taxonomic references for each genus and species • Appendix with major references for each country • Complete bibliography of all references cited in text and appendix • Index of 12,500 primary snake names The data on type specimens includes museum and catalog number, length and sex, and collector and date. The listed type localities include restrictions and corrections. The bibliography provides complete citations of all references cited in the text and appendix, and taxonomic comments are given in the remarks sections. This standard reference supplies a scientific, academic, and professional treatment of snakes-appealing to conservationists and herpetologists as well as zoologists, naturalists, hobbyists, researchers, and teachers.
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Phylogenies are increasingly used in all fields of medical and biological research. Moreover, because of the next generation sequencing revolution, datasets used for conducting phylogenetic analyses grow at an unprecedented pace. RAxML (Randomized Axelerated Maximum Likelihood) is a popular program for phylogenetic analyses of large datasets under maximum likelihood. Since the last RAxML paper in 2006, it has been continuously maintained and extended to accommodate the increasingly growing input datasets and to serve the needs of the user community. I present some of the most notable new features and extensions of RAxML, such as, a substantial extension of substitution models and supported data types, the introduction of SSE3, AVX, and AVX2 vector intrinsics, techniques for reducing the memory requirements of the code and a plethora of operations for conducting post-analyses on sets of trees. In addition, an up-to-date, 50 page user manual covering all new RAxML options is available. The code is available under GNU GPL at https://github.com/stamatak/standard-RAxML. Alexandros.Stamatakis@h-its.org.
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Vertebral and cranial remains of elapid snakes have been collected from fossil assemblages at Riversleigh, north-west Queensland, Australia; most are Miocene but one may be late Oligocene and another as young as Pliocene. The oldest specimen (probably the oldest elapid yet known anywhere) is a vertebra that can be referred provisionally to the extant taxon Laticauda (Hydrophiinae, sensu Slowinski and Keogh, 2000), implying that the basal divergences among Australasian hydrophiine lineages had occurred by the early Miocene, in contrast to most previous estimates for the age of this geographically isolated adaptive radiation. Associated vertebrae and jaw elements from a Late Miocene deposit are described as Incongruelaps iteratus nov. gen. et sp., which has a unique combination of unusual derived characters otherwise found separately in several extant hydrophiine taxa that are only distantly related. Associated vertebrae from other sites, and two parietals from a possibly Pliocene deposit, suggest the presence of several other taxa distinct from extant forms, but the amount of material (and knowledge of variation in extant taxa) is currently insufficient to diagnose these forms. The Tertiary elapids of Riversleigh thus appear to be relatively diverse taxonomically, but low in abundance and, with one exception, not referable to extant taxa below the level of Hydrophiinae. This implies that the present diversity of hydrophiine elapids (31 recognized terrestrial genera, and approximately 16 marine) represents the result of substantial extinction as well as the “cone of increasing diversity” that could be inferred from phylogenetic studies on extant forms.
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The Béon 1 vertebrate locality, formerly known as "Montréal-du-Gers" in southwestern France, has yielded a rich fauna of amphibians and squamate reptiles of late early Miocene (MN 4; Orleanian) age. It represents the first herpetofauna of that age described from Western Europe. The assemblage from Béon 1 includes 26 species (three species of salamanders, two of anurans, seven of lizards, and 14 of snakes). At least as far as snakes are concerned, the appearance of such a diversity of taxa is typical of the zone MN 4. The presence of this diverse snake assemblage at Béon 1 demonstrates that the wave of modern taxa that invaded Central Europe during MN 4 also reached Western Europe. The number and diversity of natricine snakes appear to be a characteristic of the late early Miocene (MN 4) and also of the early middle Miocene. Although a change apparently took place between the herpetofaunas from MN 4 and MN 6 in Central Europe, Béon 1 shows that the faunas were not altered significantly during that period in Western Europe. Béon 1 has produced the earliest Pseudopus laurillardi (Anguidae), Python europaeus (Boidae), Coluber pouchetii, Texasophis meini, Neonatrix europaea, and Neonatrix natricoides (Colubridae). It has also yielded one of the earliest Varanus (Varanidae) and perhaps the youngest Natrix merkurensis (Colubridae). The knowledge of the anatomy of the anguid lizard Pseudopus laurillardi is increased by the description of a posterior braincase. The abundance of aquatic amphibians and snakes confirms the presence of lacustrine/swampy environment.
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Background The extant squamates (>9400 known species of lizards and snakes) are one of the most diverse and conspicuous radiations of terrestrial vertebrates, but no studies have attempted to reconstruct a phylogeny for the group with large-scale taxon sampling. Such an estimate is invaluable for comparative evolutionary studies, and to address their classification. Here, we present the first large-scale phylogenetic estimate for Squamata. Results The estimated phylogeny contains 4161 species, representing all currently recognized families and subfamilies. The analysis is based on up to 12896 base pairs of sequence data per species (average = 2497 bp) from 12 genes, including seven nuclear loci (BDNF, c-mos, NT3, PDC, R35, RAG-1, and RAG-2), and five mitochondrial genes (12S, 16S, cytochrome b, ND2, and ND4). The tree provides important confirmation for recent estimates of higher-level squamate phylogeny based on molecular data (but with more limited taxon sampling), estimates that are very different from previous morphology-based hypotheses. The tree also includes many relationships that differ from previous molecular estimates and many that differ from traditional taxonomy. Conclusions We present a new large-scale phylogeny of squamate reptiles that should be a valuable resource for future comparative studies. We also present a revised classification of squamates at the family and subfamily level to bring the taxonomy more in line with the new phylogenetic hypothesis. This classification includes new, resurrected, and modified subfamilies within gymnophthalmid and scincid lizards, and boid, colubrid, and lamprophiid snakes.
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ABStRACt We present a molecular phylogenetic analysis of caenophidian (advanced) snakes using sequences from two mitochondrial genes (12S and 16S rRNA) and one nuclear (c‑mos) gene (1681 total base pairs), and with 131 terminal taxa sampled from throughout all major caenophidian lineages but focussing on Neotropical xenodontines. Direct optimization parsimony analysis resulted in a well‑resolved phylogenetic tree, which corroborates some clades identified in previous analyses and suggests new hypotheses for the composition and relationships of others. The major salient points of our analysis are: (1) placement of Acrochordus, Xenodermatids, and Pareatids as successive outgroups to all remaining caenophidians (including viperids, elapids, atractaspidids, and all other "colubrid" groups); (2) within the latter group, viperids and homalopsids are sucessive sister clades to all remaining snakes; (3) the following monophyletic clades within crown group caenophidians: Afro‑Asian psammophiids (including Mimophis from Madagascar), Elapidae (including hydrophiines but excluding Homoroselaps), Pseudoxyrhophiinae, Colubrinae, Natricinae, Dipsadinae, and Xenodontinae. Homoroselaps is associated with atractaspidids. Our analysis suggests some taxonomic changes within xenodontines, including new taxonomy for Alsophis elegans, Liophis amarali, and further taxonomic changes within Xenodontini and the West Indian radiation of xenodontines. Based on our molecular analysis, we present a revised classification for caenophidians and provide morphological diagnoses for many of the included clades; we also highlight groups where much more work is needed. We name as new two higher taxonomic clades within Caenophidia, one Volume 49(11):115-153, 2009
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The early Eocene (Ypresian) Cambay Formation of Vastan Lignite Mine in Gujarat, western India, has produced a diverse assemblage of snakes including at least ten species that belong to the Madtsoiidae, Palaeophiidae (Palaeophis and Pterosphenus), Boidae, and several Caenophidia. Within the latter taxon, the Colubroidea are represented by Russellophis crassus sp. nov. (Russellophiidae) and by Procerophis sahnii gen. et sp. nov. Thaumastophis missiaeni gen. et sp. nov. is a caenophidian of uncertain family assignment. At least two other forms probably represent new genera and species, but they are not named; both appear to be related to the Caenophidia. The number of taxa that represent the Colubroidea or at least the Caenophidia, i.e., advanced snakes, is astonishing for the Eocene. This is consistent with the view that Asia played an important part in the early history of these taxa. The fossils come from marine and continental levels; however, no significant difference is evident between faunas from these levels. The fauna from Vastan Mine includes highly aquatic, amphibious, and terrestrial snakes. All are found in the continental levels, including the aquatic palaeophiids, whereas the marine beds yielded only two taxa. Vastan Mine is only the second locality in which the palaeophiids Palaeophis and Pterosphenus co-occur. The composition of the fauna from Vastan is on the whole similar to that of the early Eocene of Europe; however, comparisons with early Eocene faunas of other continents are not possible because they are poorly known or unknown.
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Ever larger phylogenies are being constructed due to the explosion of genetic data and development of high-performance phylogenetic reconstruction algorithms. However, most methods for calculating divergence times are limited to datasets that are orders of magnitude smaller than recently published large phylogenies. Here, we present an algorithm and implementation of a divergence time method using penalized likelihood that can handle datasets of thousands of taxa. We implement a method that combines the standard derivative-based optimization with a stochastic simulated annealing approach to overcome optimization challenges. We compare this approach with existing software including r8s, PATHd8 and BEAST. Source code, example files, binaries and documentation for treePL are available at https://github.com/blackrim/treePL. eebsmith@umich.edu Supplementary data are available at Bioinformatics online.
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Scanlon, John D. & Lee, Michael S. Y. (2004). Phylogeny of Australasian venomous snakes (Colubroidea, Elapidae, Hydrophiinae) based on phenotypic and molecular evidence. — Zoologica Scripta, 33, 335–366.Phylogenetic relationships among Hydrophiinae (Australasian and marine elapid snakes) are inferred using 87 characters from external, skeletal, hemipenial and internal anatomy, ecology, and chromosomes as well as available sequences of two mitochondrial genes (cytochrome b and 16S rRNA). Parsimony analysis of the combined data retrieves many widely accepted clades; while observed bootstrap or branch (Bremer) support for these is often weak, most have never been corroborated previously by a rigorous numerical analysis. Sea kraits (Laticauda) and Solomon Islands elapids are basal to the remaining hydrophiines (Australian terrestrial forms and hydrophiin sea snakes). The latter clade includes three main lineages: a large-bodied oviparous lineage, a small-bodied oviparous lineage, and a viviparous lineage (which also includes the hydrophiin sea snakes, strongly reaffirmed as monophyletic). While the Solomons retain a relictual fauna, New Guinea has less endemism and has been invaded multiple times by Australian lineages, so there is no clear ‘stepping stone’ pattern supporting a northern (Asian, rather than Gondwanan) biogeographical origin.
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We analysed patterns of animal dispersal, vicariance and diversification in the Holarctic based on complete phylogenies of 57 extant non-marine taxa, together comprising 770 species, documenting biogeographic events from the Late Mesozoic to the present. Four major areas, each corresponding to a historically persistent landmass, were used in the analyses: eastern Nearctic (EN), western Nearctic (WN), eastern Palaeoarctic (EP) and western Palaeoarctic (WP). Parsimony-based tree fitting showed that there is no significantly supported general area cladogram for the dataset. Yet, distributions are strongly phylogenetically conserved, as revealed by dispersal-vicariance analysis (DIVA). DIVA-based permutation tests were used to pinpoint phylogenetically determined biogeographic patterns. Consistent with expectations, continental dispersals (WP↔EP and WN↔EN) are significantly more common than palaeocontinental dispersals (WN↔EP and EN↔WP), which in turn are more common than disjunct dispersals (EN↔EP and WN↔WP). There is significant dispersal asymmetry both within the Nearctic (WN→EN more common than EN→WN) and the Palaeoarctic (EP→WP more common than WP→EP). Cross-Beringian faunal connections have traditionally been emphasized but are not more important than cross-Atlantic connections in our data set. To analyse changes over time, we sorted biogeographic events into four major time periods using fossil, biogeographic and molecular evidence combined with a ‘branching clock’. These analyses show that trans-Atlantic distributions (EN-WP) were common in the Early-Mid Tertiary (70-20 Myr), whereas trans-Beringian distributions (WN-EP) were rare in that period. Most EN-EP disjunctions date back to the Early Tertiary (70-45 Myr), suggesting that they resulted from division of cross-Atlantic rather than cross-Beringian distributions. Diversification in WN and WP increased in the Quaternary (< 3 Myr), whereas in EP and EN it decreased from a maximum in the Early-Mid Tertiary.
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Snake diversity varies by at least two orders of magnitude among extant lineages, with numerous groups containing only one or two species, and several young clades exhibiting exceptional richness (>700 taxa). With a phylogeny containing all known families and subfamilies, we find that these patterns cannot be explained by background rates of speciation and extinction. The majority of diversity appears to derive from a radiation within the superfamily Colubroidea, potentially stemming from the colonization of new areas and the evolution of advanced venom-delivery systems. In contrast, negative relationships between clade age, clade size, and diversification rate suggest the potential for possible bias in estimated diversification rates, interpreted by some recent authors as support for ecologically mediated limits on diversity. However, evidence from the fossil record indicates that numerous lineages were far more diverse in the past, and that extinction has had an important impact on extant diversity patterns. Thus, failure to adequately account for extinction appears to prevent both rate- and diversity-limited models from fully characterizing richness dynamics in snakes. We suggest that clade-level extinction may provide a key mechanism for explaining negative or hump-shaped relationships between clade age and diversity, and the prevalence of ancient, species-poor lineages in numerous groups.
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Fossil snakes from the Uppermost Miocene (NM 13) of Algora (Guadalajara, Spain) are described, The fol1owing forms have been recognized: Scolecophidia indet., Elaphe algorensis sp. nov. and Hispanophis coronelloideus gen. et sp, nov. (Colubridae), Naja iberica sp. nov. (Elapidae), Viperidae indet. This faunistic assemblage, being uncomparable with any other snake fauna of Europe, includes both endemic forms (colubrids) as well as close relatives of North African species ( Naja iberica sp. nov., may be also vipers). Se estudian los restos de ofidios del Mioceno terminal (MN 13) de Algora (Guadalajara, España). Se han detectado las siguientes formas, Scolecophidia indet., Elaphe algorensis sp. nov. e Hispanophis coronelloideus gen. sp, nov. (Colubridae), Naja iberica sp. nov. (Elapidae), y Viperidae indet. Esta asociación faunística no es comparable a las restantes faunas de ofidios conocidas de otras localidades europeas, e incluye tanto formas endémicas (Colubridae), como especies evolutivamente emparentadas con formas norteafricanas ( Naja iberica sp. nov., quizás también las víboras).
Article
The venomous snake subfamily Hydrophiinae includes more than 40 genera and approximately 200 species. Most members of this clade inhabit Australia, and have been well studied. But, because of poor taxon sampling of Melanesian taxa, basal evolutionary relationships have remained poorly resolved. The Melanesian genera Ogmodon, Loveridgelaps, and Salomonelaps have not been included in recent phylogenetic studies, and the New Guinean endemic, Toxicocalamus, has been poorly sampled and sometimes recovered as polyphyletic. We generated a multilocus phylogeny for the subfamily using three mitochondrial and four nuclear loci so as to investigate relationships among the basal hydrophiine genera and to determine the status of Toxicocalamus. We sequenced these loci for eight of the 12 described species within Toxicocalamus, representing the largest molecular data set for this genus. We found that a system of offshore island arcs in Melanesia was the centre of origin for terrestrial species of Hydrophiinae, and we recovered Toxicocalamus as monophyletic. Toxicocalamus demonstrates high genetic and morphological diversity, but some of the molecular diversity is not accompanied by diagnostic morphological change. We document at least five undescribed species that all key morphologically to Toxicocalamus loriae (Boulenger, 1898), rendering this species polyphyletic. Continued work on Toxicocalamus is needed to document the diversity of this genus, and is likely to result in the discovery of additional species. Our increased taxon sampling allowed us to better understand the evolution and biogeography of Hydrophiinae; however, several unsampled lineages remain, the later study of which may be used to test our biogeographic hypothesis.
Article
A summary is presented of classification of extant snakes down to the tribe level, based primarily upon and extrapolated from McDowell's higher-category taxa, but incorporating other recent innovations as well. Dates and authorities are provided for each taxon in all categories. The system incorporates 2 infraorders of Serpentes, one with 3 families, the other with 6 superfamilies and 12 families. Six of the latter families contain subfamilies, with 2 each in 5 and 28 in the other, for a total of 38 subfamilies. Among the proteroglyphs, 17 tribes are recognized in the 2 families and 4 subfamilies, and in the solenoglyphs 4 tribes are listed for the 2 subfamilies of one family.
Article
The phylogenetic relationships of 18 species of New World coral snakes (Elapidae: Leptomicrurus, Micruroides, and Micrurus) were examined with morphological and allozymic characters analyzed by parsimony. Two species of kraits (Elapidae: Bungarus) were included as outgroups. Coral snake morphology was found to be very conservative and few informative morphological characters were found. The general relationships of all coral snakes are discussed in light of the morphological synapomorphies identified in this study. The results indicate that Micrurus is paraphyletic because of the exclusion of Leptomicrurus. This is rectified by placing Leptomicrurus into the synonymy of Micrurus.
Article
The paper reviews the entire fossil record of the Colubridae coming from the European Early Oligocene (MP21) to late Early Pliocene (MN 15) localities. Prior to the end of the Early Miocene, European colubrids were rare and dominated by booid snakes. At the end of the Early Miocene (MN4), the archaic ophidian fauna of Europe was literally flooded by eastern immigrants, principally representatives of the colubroid families Colubridae, Elapidae, and Viperidae. Since then, the Colubridae became a dominant group in snake assemblages, both in Europe and elsewhere. The rich colubrid fauna inhabiting the European continent in the Middle Miocene (MN5 to 7+8) was composed exclusively of extinct species, representing mainly fossil genera, although members of living genera were also quite common. At the beginning of the Late Miocene (MN9), almost all fossil genera became extinct, but living genera were represented exclusively by fossil species. In the late Early Pliocene (MN 15), almost all European colubrids were living species. The Late Pliocene (MN 16) and Pleistocene colubrid snakes did not differ from those inhabiting Europe today.
Article
Some basic osteological cranial features of living and fossil members of the genus Naja are described. The extinct genus Palaeonaja Hoffstetter, 1939, is synonymized with the modern Naja Laurenti, 1768, and the extinct species Palaeonaja crassa Hoffstetter, 1939, is synonymized with Naja romani (Hoffstetter, 1939). Anatomically, the genus Naja can be divided into two main complexes, composed of: (1) living African species, N. antiqua from the Moroccan Miocene, and N. iberica from the Spanish Miocene; (2) living Asiatic species and N. romani from the Miocene of France, Austria, and Ukraine. Living members of the Asiatic complex make up a monophyletic group; they belong to at least three distinct lineages: N. oxiana, N. naja s.s. ( = N. naja naja), and the remaining taxa named here informally the 'East Asiatic Naja'. The African complex is thought to be most primitive and perhaps paraphyletic; Africa is presumed to be the centre of earliest radiation of the genus. The precise relationships of Walterinnesia, a close relative of Naja occupying the area between Asiatic and African ranges of Naja, remain unclear.
Article
The venoms of coral snakes (genus Micrurus) are known to induce a broad spectrum of pharmacological activities. While some studies have investigated their potential human effects, little is known about their mechanism of action in terms of the ecological diversity and evolutionary relationships among the group. In the current study we investigated the neuromuscular blockade of the venom of two sister species Micrurus mipartitus and Micrurus dissoleucus, which exhibit divergent ecological characteristics in Colombia, by using the chick biventer cervicis nerve-muscle preparation. We also undertook a phylogenetic analysis of these species and their congeners, in order to provide an evolutionary framework for the American coral snakes. The venom of M. mipartitus caused a concentration-dependant inhibition (3-10 μg/ml) of nerve-mediated twitches and significantly inhibited contractile responses to exogenous ACh (1 mM), but not KCl (40 mM), indicating a postsynaptic mechanism of action. The inhibition of indirect twitches at the lower venom dose (3 μg/ml) showed to be triphasic and the effect was further attenuated when PLA2 was inhibited. M. dissoleucus venom (10-50 μg/ml) failed to produce a complete blockade of nerve-mediated twitches within a 3 h time period and significantly inhibited contractile responses to exogenous ACh (1 mM) and KCl (40 mM), indicating both postsynaptic and myotoxic mechanisms of action. Myotoxic activity was confirmed by morphological studies of the envenomed tissues. Our results demonstrate a hitherto unsuspected diversity of pharmacological actions in closely related species which exhibit divergent ecological characteristics; these results have important implications for both the clinical management of Coral snake envenomings and the design of Micrurus antivenom.
Article
The superfamily Colubroidea (> 2500 species) includes the majority of snake species and is one of the most conspicuous and well-known radiations of terrestrial vertebrates. However, many aspects of the phylogeny of the group remain contentious, and dozens of genera have yet to be included in molecular phylogenetic analyses. We present a new, large-scale, likelihood-based phylogeny for the colubroids, including 761 species sampled for up to five genes: cytochrome b (93% of 761 species sampled), ND4 (69%), ND2 (28%), c-mos (54%), and RAG-1 (13%), totaling up to 5814bp per species. We also compare likelihood bootstrapping and a recently proposed ultra-fast measure of branch support (Shimodaira-Hasegawa-like [SHL] approximate likelihood ratio), and find that the SHL test shows strong support for several clades that were weakly-supported by bootstrapping in this or previous analyses (e.g., Dipsadinae, Lamprophiidae). We find that SHL values are positively related to branch lengths, but show stronger support for shorter branches than bootstrapping. Despite extensive missing data for many taxa (mean=67% per species), neither bootstrap nor SHL support values for terminal species are related to their incompleteness, and that most highly incomplete taxa are placed in the expected families from previous taxonomy, typically with very strong support. The phylogeny indicates that the Neotropical colubrine genus Scaphiodontophis represents an unexpectedly ancient lineage within Colubridae. We present a revised higher-level classification of Colubroidea, which includes a new subfamily for Scaphiodontophis (Scaphiodontophiinae). Our study provides the most comprehensive phylogeny of Colubroidea to date, and suggests that SHL values may provide a useful complement to bootstrapping for estimating support on likelihood-based trees.
Article
Acrochordus is a species-poor but highly distinctive aquatic snake genus currently distributed from India to the western edge of the Pacific. We provide the first phylogeny for the three extant species using Bayesian and parsimony analyses of one mitochondrial and two nuclear gene sequences. Acrochordus javanicus is strongly recovered as sister to A. arafurae+A. granulatus, counter to expectations from superficial ecology, external phenotype and former taxonomy. We review and revise key fossil calibrations for dating snake divergences. Bayesian relaxed-clock analysis of the two nuclear loci yields deep interspecific divergences among extant species that occurred during the Miocene approximately 16 and approximately 20Mya (million years ago), pre-dating at least two of the three other living marine snake lineages. New morphological data for A. arafurae, and our molecular timescale, provide support for the placement of fossil taxon A. dehmi within the Acrochordus crown group, as sister to A. javanicus among nominate species. Finally, Acrochordus phylogeny provides an improved basis for taxon selection and character polarization in higher snake phylogenetics. Our study highlights the three Acrochordus species as old and highly distinct lineages that comprise an important component of the threatened Indo-Australian biodiversity.
Article
Remains of Neogene and Quaternary "natricine" colubrids, elapids and viperids, including snakes previously described and those undescribed yet, coming from Poland, Ukraine, Moldavia, Czechoslovakia, Austria, Hungary, Romania, Bulgaria, and Greece are discussed. The following taxa, including 11 extinct species, were recognized: "Natricinae": Neonatrix nova, Neonatrix sp., Palaeonatrix silesiaca, Palaeonatrix lehmani, Natrix longivertebrata, Natrix cf. N. longivertebrata, Natrix natrix, Natrix tesselata, Natrix cf. N. tesselata, Natrix sp., "Natricinae" indet.; Elapidae: Naja romani, Naja sp., cf. Naja sp. ; Viperidae: Vipera platyspondyla, Vipera sarmatica, Vipera burgenlandica, Vipera gedulyi, Vipera kuchurganica, Vipera antiqua, Vipera cf. V. ammodytes, Vipera berus, Vipera sp ('Oriental vipers' group), Vipera sp. ('aspis' group), Vipera sp. ('berus' group), Vipera sp. . (status unknown). Taxonomic status of two other extinct species, Natrix parva and Laophis crotaloides , is uncertain. Modern species appeared fírst in Central and East Europe in the middle Pliocene (MN 15). Older snakes belonged to extinct species of either extinct or extant genera; taxonomic distinction of most extinct genera is, however, not fully demonstrated. Best recognized oldest snakes from the area (Elapidae, Viperidae, and sorne Colubridae) are clearly referable to modern genera and intrageneric subdivisions occurring today are observed in oldest (Iower Miocene) remains; closest living relatives of these fossils are presently distributed in the Oriental Realm. Se revisan y estudian los restos neógenos y cuaternarios de colúbridos «natricinos», elápidos y vipéridos, incluyendo tanto serpientes previamente descritas como- otras inéditas. Los materiales analizados proceden de Polonia, Ukrania, Moldavia, Checoslovaquia, Austria, Hungría, Rumania, Bulgaria y Grecia. Se reconocen los siguientes taxones, incluyendo 11 especies extinguidas: Natricinae: Neonatrix nova, Neonatrix sp., Palaeonatrix silesiaca, Palaeonatrix lehmani, Natrix longivertebrata, Natrix cf. N. longivertebrata, Natrix natrix, Natrix tesselata, Natrix cf. N. tesselata, Natrix sp., «Natricinae» indet.; Elapidae: Naja romani, Naja sp., cf. Naja sp. ; Viperidae: Vipera plastyspondyla, Vipera sarmatica, Vipera burgenlandica, Vipera gedulyi, Vipera kuchurganica, Vipera antiqua, Vipera cf. V. ammodytes, Vipera berus, Vipera sp. («grupo Oriental»), Vipera sp. (grupo «aspis» ), Vipera sp. (grupo «berus» ), Vipera sp. (relaciones desconocidas). El estatus taxonómico de otras dos especies extintas, Natrix parva y Laophis crotaloides , es poco claro. Las especies actuales aparecen primero en Europa central y oriental durante el Plioceno medio (MN 15), mientras que las serpientes más antiguas pertenecen a especies extinguidas, incluidas tanto en géneros actuales como también en otros ya extinguidos. La validez taxonómica como entes independientes de muchos géneros extintos no está plenamente demostrada. Las serpientes bien conocidas más antiguas del área (Elapidae, Viperidae, algunos Colubridae) son claramente adscribibles a géneros actuales, y las subdivisiones intragenéricas actualmente existentes pueden ya observarse en los restos más antiguos (Mioceno inferior). Formas actuales cercanas a estos fósiles miocénicos se encuentran distribuidos en la Region Biogeográfíca Oriental.
Article
Despite their medical interest, the phylogeny of the snake family Viperidae remains inadequately understood. Previous studies have generally focused either on the pitvipers (Crotalinae) or on the Old World vipers (Viperinae), but there has been no comprehensive molecular study of the Viperidae as a whole, leaving the affinities of key taxa unresolved. Here, we infer the phylogenetic relationships among the extant genera of the Viperidae from the sequences of four mitochondrial genes (cytochrome b, NADH subunit 4, 16S and 12S rRNA). The results confirm Azemiops as the sister group of the Crotalinae, whereas Causus is nested within the Viperinae, and thus not a basal viperid or viperine. Relationships among the major clades of Viperinae remain poorly resolved despite increased sequence information compared to previous studies. Bayesian molecular dating in conjunction with dispersal-vicariance analysis suggests an early Tertiary origin in Asia for the crown group Viperidae, and rejects suggestions of a relatively recent, early to mid-Tertiary origin of the Caenophidia.
Article
Published molecular phylogenetic studies of elapid snakes agree that the marine and Australo-Melanesian forms are collectively monophyletic. Recent studies, however, disagree on the relationships of the African, American, and Asian forms. To resolve the relationships of the African, American, and Asian species to each other and to the marine/Australo-Melanesian clade, we sequenced the entire cytochrome b gene for 28 elapids; 2 additional elapid sequences from GenBank were also included. This sample includes all African, American, and Asian genera (except for the rare African Pseudohaje), as well as a representative sample of marine/Australo-Melanesian genera. The data were analyzed by the methods of maximum-parsimony and maximum-likelihood. Both types of analyses yielded similar trees, from which the following conclusions can be drawn: (1) Homoroselaps falls outside a clade formed by the remaining elapids; (2) the remaining elapids are divisible into two broad sister clades, the marine/Australo-Melanesian species vs the African, American, and Asian species; (3) American coral snakes cluster with Asian coral snakes; and (4) the "true" cobra genus Naja is probably not monophyletic as the result of excluding such genera as Boulengerina and Paranaja.
Article
Rates of molecular evolution vary widely between lineages, but quantification of how rates change has proven difficult. Recently proposed estimation procedures have mainly adopted highly parametric approaches that model rate evolution explicitly. In this study, a semiparametric smoothing method is developed using penalized likelihood. A saturated model in which every lineage has a separate rate is combined with a roughness penalty that discourages rates from varying too much across a phylogeny. A data-driven cross-validation criterion is then used to determine an optimal level of smoothing. This criterion is based on an estimate of the average prediction error associated with pruning lineages from the tree. The methods are applied to three data sets of six genes across a sample of land plants. Optimally smoothed estimates of absolute rates entailed 2- to 10-fold variation across lineages.
Fossil snakes from Laetoli
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Phylogenetic affinities of the fossil elapids Naja romani and Naja antiqua (Serpentes, Elapidae)
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QUADROS, A.B., K. MAHLOW, N.-E. JALIL, AND H. ZAHER. 2019. Phylogenetic affinities of the fossil elapids Naja romani and Naja antiqua (Serpentes, Elapidae). Journal of Morphology 280 (S1): S207.
es s ua ates du Mioce ne de Beni Mellal
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Palaeontology of the Orange River Valley, Namibia. Memoir of the Geology Survey of Namibia
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RAGE, J.C., AND J.A. HOLMAN. 1984. Des serpents (Reptilia, ua ata de type norda e ricain dans le Mioce ne française. E olution paralle le ou dispersion? Geobios 17: 89-104.
Multilocus phylogeny and recent rapid radiation of the viviparous sea snakes (Elapidae: Hydrophiinae)
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SANDERS, K.L., M.S.Y. LEE, MUMPUNI, T. BERTOZZI, AND A.R. RASMUSEN. 2013. Multilocus phylogeny and recent rapid radiation of the viviparous sea snakes (Elapidae: Hydrophiinae). Molecular Phylogenetics and Evolution 66: 575-591.
Neogene cobras of the genus Naja (Serpentes, Elapidae) of east Europe
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SZYNDLAR, Z., AND G.A. ZEROVA. 1990. Neogene cobras of the genus Naja (Serpentes, Elapidae) of east Europe. Annalen des Naturhistorischen Museums in Wien 91A: 53-61.
2019. The Reptile Database <www.reptiledatabase.org>
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The American herpetofauna and the interchange
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VANZOLINI, P.E., AND W.R. HEYER. 1985. The American herpetofauna and the interchange. Pp. 475-487 In Stehli, F. G., and S. D. Webb (Eds.), The Great American Biotic Interchange. Plenum Press, New York, New York, United States.
Origem e Evolução dos Elapídeos e das cobras-corais do Novo Mundo
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ZAHER, H., F.G. GRAZZIOTIN, A.L.C PRUDENTE, AND N. J. SILVA, JR. 2016. Origem e Evolução dos Elapídeos e das cobras-corais do Novo Mundo. Pp. 24-45 In Silva Jr., N.J. (Org.), As cobras-corais do Brasil: biologia, taxonomia, venenos e envenenamentos. Ed. Da PUC Goiás, Goiânia, Brazil.
Texasophis galbreathi (Holman, 1984)-Set as the MRCA of Coluber constrictor and Heterodon platirhinos (Colubridae stem clade)
  • Appendix I Phylogenetic
  • Employed
APPENDIX I. PHYLOGENETIC ANALYSIS EMPLOYED (2) Texasophis galbreathi (Holman, 1984)-Set as the MRCA of Coluber constrictor and Heterodon platirhinos (Colubridae stem clade).
Set as the MRCA of Homalopsis buccata and Azemiops feae (Viperidae stem clade). The earliest date used for the clade was 54 MA and the most recent was 19
  • Indet Viperidae Gen
  • Kuch
Viperidae gen. and sp. indet. (Kuch et al., 2006)-Set as the MRCA of Homalopsis buccata and Azemiops feae (Viperidae stem clade). The earliest date used for the clade was 54 MA and the most recent was 19.5 MA.
Set the MRCA of Naja naja and Rhamphiophis oxyrhynchus (Elapidae stem clade)
  • Indet Elapidae Gen
  • Kuch
Elapidae gen. and sp. indet. (Kuch et al., 2006)-Set the MRCA of Naja naja and Rhamphiophis oxyrhynchus (Elapidae stem clade).