RESUMO
Crotalines (pitvipers) in the Americas are distributed from southern Canada to southern Argentina, and are represented by 13 genera and 163 species that constitute a monophyletic group. Their phylogenetic relationships have been assessed mostly based on DNA sequences, while morphological data have scarcely been used for phylogenetic inquiry. We present a total-evidence phylogeny of New World pitvipers, the most taxon/character comprehensive phylogeny to date. Our analysis includes all genera, morphological data from external morphology, cranial osteology and hemipenial morphology, and DNA sequences from mitochondrial and nuclear genes. We performed analyses with parsimony as an optimality criterion, using different schemes for character weighting. We evaluated the contribution of the different sources of characters to the phylogeny through analyses of reduced datasets and calculation of weighted homoplasy and retention indexes. We performed a morphological character analysis to identify synapomorphies for the main clades. In terms of biogeography, our results support a single colonization event of the Americas by pitvipers, and a cladogenetic event into a Neotropical clade and a North American/Neotropical clade. The results also shed light on the previously unstable position of some taxa, although they could not sufficiently resolve the position of Bothrops lojanus, which may lead to the paraphyly of either Bothrops or Bothrocophias. The morphological character analyses demonstrated that an important phylogenetic signal is contained in characters related to head scalation, the jaws and the dorsum of the skull, and allowed us to detect morphological convergences in external morphology associated with arboreality.
Assuntos
Bothrops , Crotalinae , Viperidae , Animais , Filogenia , Viperidae/genética , Crotalinae/genética , Evolução Biológica , Sequência de Bases , Bothrops/genéticaRESUMO
Crotalines (pitvipers) in the Americas are distributed from southern Canada to southern Argentina, and are represented by 13 genera and 163 species that constitute a monophyletic group. Their phylogenetic relationships have been assessed mostly based on DNA sequences, while morphological data have scarcely been used for phylogenetic inquiry. We present a total-evidence phylogeny of New World pitvipers, the most taxon/character comprehensive phylogeny to date. Our analysis includes all genera, morphological data from external morphology, cranial osteology and hemipenial morphology, and DNA sequences from mitochondrial and nuclear genes. We performed analyses with parsimony as an optimality criterion, using different schemes for character weighting. We evaluated the contribution of the different sources of characters to the phylogeny through analyses of reduced datasets and calculation of weighted homoplasy and retention indexes. We performed a morphological character analysis to identify synapomorphies for the main clades. In terms of biogeography, our results support a single colonization event of the Americas by pitvipers, and a cladogenetic event into a Neotropical clade and a North American/Neotropical clade. The results also shed light on the previously unstable position of some taxa, although they could not sufficiently resolve the position of Bothrops lojanus, which may lead to the paraphyly of either Bothrops or Bothrocophias. The morphological character analyses demonstrated that an important phylogenetic signal is contained in characters related to head scalation, the jaws and the dorsum of the skull, and allowed us to detect morphological convergences in external morphology associated with arboreality.
RESUMO
South American racers of the tribe Philodryadini are a widespread and diverse group of Neotropical snakes with a complex taxonomic and systematic history. Recent studies failed to present a robust phylogenetic hypothesis for the tribe, mainly due to incomplete taxon sampling. Here we provide the most extensive molecular phylogenetic analysis of Philodryadini available so far, including 20 species (83% of the known diversity) from which six were not sampled previously. Our results reveal that Philodryadini is not monophyletic, but instead includes a central Andean clade formed by Philodryas simonsii, P. tachymenoides, and P. amaru, and a southern and cis-Andean clade including all remaining philodryadines. This discovery requires resurrection of two genera as well as erection of a new tribe of Xenodontinae for the central Andean clade. Within the southern and cis-Andean radiation, our analyses resolve a basal dichotomy separating two main lineages: Clade A, containing the Common Green Racers P. laticeps and P. viridissima and the South American Vine snakes P. georgeboulengeri and P. argentea; and Clade B, including the remaining species of Philodryas sensu stricto. We resurrect the genera Chlorosoma and Xenoxybelis to better represent the monophyly of lineages within the southern and cis-Andean clade.(AU)
Assuntos
Animais , Serpentes/anatomia & histologia , Serpentes/classificação , Serpentes/genética , Filogenia , Classificação , Código de Barras de DNA Taxonômico , América do SulRESUMO
South American racers of the tribe Philodryadini are a widespread and diverse group of Neotropical snakes with a complex taxonomic and systematic history. Recent studies failed to present a robust phylogenetic hypothesis for the tribe, mainly due to incomplete taxon sampling. Here we provide the most extensive molecular phylogenetic analysis of Philodryadini available so far, including 20 species (83% of the known diversity) from which six were not sampled previously. Our results reveal that Philodryadini is not monophyletic, but instead includes a central Andean clade formed by Philodryas simonsii, P. tachymenoides, and P. amaru, and a southern and cis-Andean clade including all remaining philodryadines. This discovery requires resurrection of two genera as well as erection of a new tribe of Xenodontinae for the central Andean clade. Within the southern and cis-Andean radiation, our analyses resolve a basal dichotomy separating two main lineages: Clade A, containing the Common Green Racers P. laticeps and P. viridissima and the South American Vine snakes P. georgeboulengeri and P. argentea; and Clade B, including the remaining species of Philodryas sensu stricto. We resurrect the genera Chlorosoma and Xenoxybelis to better represent the monophyly of lineages within the southern and cis-Andean clade.
Assuntos
Animais , Classificação , Filogenia , Serpentes/anatomia & histologia , Serpentes/classificação , Serpentes/genética , América do Sul , Código de Barras de DNA TaxonômicoRESUMO
Abstract South American racers of the tribe Philodryadini are a widespread and diverse group of Neotropical snakes with a complex taxonomic and systematic history. Recent studies failed to present a robust phylogenetic hypothesis for the tribe, mainly due to incomplete taxon sampling. Here we provide the most extensive molecular phylogenetic analysis of Philodryadini available so far, including 20 species (83% of the known diversity) from which six were not sampled previously. Our results reveal that Philodryadini is not monophyletic, but instead includes a central Andean clade formed by Philodryas simonsii, P. tachymenoides, and P. amaru, and a southern and cis-Andean clade including all remaining philodryadines. This discovery requires resurrection of two genera as well as erection of a new tribe of Xenodontinae for the central Andean clade. Within the southern and cis-Andean radiation, our analyses resolve a basal dichotomy separating two main lineages: Clade A, containing the Common Green Racers P. laticeps and P. viridissima and the South American Vine snakes P. georgeboulengeri and P. argentea; and Clade B, including the remaining species of Philodryas sensu stricto. We resurrect the genera Chlorosoma and Xenoxybelis to better represent the monophyly of lineages within the southern and cis-Andean clade.
RESUMO
We describe a new species of pitviper of the genus Bothrops from the Peruvian Pampas del Heath, in the Bahuaja-Sonene National Park. Pampas del Heath is an area of seasonally flooded savannas and a northwestern extension of the Gran Chaco Boliviano-Paraguayo. The new species is easily distinguished from its congeners by the exclusive combination of dorsal color pattern of body consisting of small C-shaped blotches, postocular stripe originating posteriorly to the eye, covering posterior supralabials, dorsum of the head with paired markings arranged symmetrically, venter cream heavily speckled with brown, prelacunal scale discrete in contact with second supralabial, three to five prefoveals, subfoveal single usually present, postfoveals absent to two, canthals two, seven intersupraoculars, one or two suboculars, two or three postoculars, seven or eight supralabials, nine to eleven infralabials, 26-27 interrictals, 23-25 middorsal scales, 172 ventrals in the female and 169-173 in males, 45 subcaudals in the female and 50 in males. We performed separate and combined phylogenetic analyses based on morphology and five mitochondrial genes and recovered the new species as a member of the Bothrops neuwiedi species group. All lineages of this clade inhabit the South American dry diagonal. This novel species of pitviper increases the known diversity of the genus Bothrops and adds to the number of described taxa from the unique and scarcely known ecosystem of Pampas del Heath.
Assuntos
Bothrops , Crotalinae , Viperidae , Animais , Ecossistema , Feminino , Masculino , Peru , FilogeniaRESUMO
We describe a new species of pitviper of the genus Bothrops from the Peruvian Pampas del Heath, in the Bahuaja-Sonene National Park. Pampas del Heath is an area of seasonally flooded savannas and a northwestern extension of the Gran Chaco Boliviano-Paraguayo. The new species is easily distinguished from its congeners by the exclusive combination of dorsal color pattern of body consisting of small C-shaped blotches, postocular stripe originating posteriorly to the eye, covering posterior supralabials, dorsum of the head with paired markings arranged symmetrically, venter cream heavily speckled with brown, prelacunal scale discrete in contact with second supralabial, three to five prefoveals, subfoveal single usually present, postfoveals absent to two, canthals two, seven intersupraoculars, one or two suboculars, two or three postoculars, seven or eight supralabials, nine to eleven infralabials, 26-27 interrictals, 23-25 middorsal scales, 172 ventrals in the female and 169-173 in males, 45 subcaudals in the female and 50 in males. We performed separate and combined phylogenetic analyses based on morphology and five mitochondrial genes and recovered the new species as a member of the Bothrops neuwiedi species group. All lineages of this clade inhabit the South American dry diagonal. This novel species of pitviper increases the known diversity of the genus Bothrops and adds to the number of described taxa from the unique and scarcely known ecosystem of Pampas del Heath.