title: Discovery of a new family of amphibians from northeast India with ancient links to Africa.
abstract: The limbless, primarily soil-dwelling and tropical caecilian amphibians (Gymnophiona) comprise the least known order of tetrapods. On the basis of unprecedented extensive fieldwork, we report the discovery of a previously overlooked, ancient lineage and radiation of caecilians from threatened habitats in the underexplored states of northeast India. Molecular phylogenetic analyses of mitogenomic and nuclear DNA sequences, and comparative cranial anatomy indicate an unexpected sister-group relationship with the exclusively African family Herpelidae. Relaxed molecular clock analyses indicate that these lineages diverged in the Early Cretaceous, about 140 Ma. The discovery adds a major branch to the amphibian tree of life and sheds light on both the evolution and biogeography of caecilians and the biotic history of northeast India-an area generally interpreted as a gateway between biodiversity hotspots rather than a distinct biogeographic unit with its own ancient endemics. Because of its distinctive morphology, inferred age and phylogenetic relationships, we recognize the newly discovered caecilian radiation as a new family of modern amphibians.
authors.affiliation: Department of Environmental Studies, Systematics Laboratory, Centre for Environmental Management of Degraded Ecosystems, University of Delhi, Delhi, 110 007, India.
authors.forename: Rachunliu G
authors.initials: RG
authors.lastname: Kamei
authors.forename: Diego
authors.initials: D
authors.lastname: San Mauro
authors.forename: David J
authors.initials: DJ
authors.lastname: Gower
authors.forename: Ines
authors.initials: I
authors.lastname: Van Bocxlaer
authors.forename: Emma
authors.initials: E
authors.lastname: Sherratt
authors.forename: Ashish
authors.initials: A
authors.lastname: Thomas
authors.forename: Suresh
authors.initials: S
authors.lastname: Babu
authors.forename: Franky
authors.initials: F
authors.lastname: Bossuyt
authors.forename: Mark
authors.initials: M
authors.lastname: Wilkinson
authors.forename: S D
authors.initials: SD
authors.lastname: Biju
mesh_terms: D000349:Africa; D000663:Amphibians / Q000033:anatomy & histology / Q000145:classification* / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D004272:DNA, Mitochondrial / Q000235:genetics; D003710:Demography; D056727:Endangered Species; D019143:Evolution, Molecular; D014644:Genetic Variation; D006239:Haplotypes / Q000235:genetics; D007194:India; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D017422:Sequence Analysis, DNA; D012886:Skull / Q000033:anatomy & histology*; D014057:Tomography, X-Ray Computed
chemical_list: D004272:DNA, Mitochondrial