Morphology of Chikilidae fam. nov.
— Chikila fulleri (Alcock, 1904) in life, brooding egg clutch (in captivity).
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.
Keywords: caecilian amphibians; Chikilidae; new family; systematics; northeast India
Amphibia L., 1758
Gymnophiona Raﬁnesque, 1814
Stegokrotaphia Cannatella & Hillis, 1993
Teresomata Wilkinson & Nussbaum, 2006
Chikilidae fam. nov.
Chikila gen. nov.
Etymology: Chikila is a northeast (Meghalaya state) Indian tribal name for the included caecilian
Type species: Herpele fulleri Alcock, 1904.
Volume reconstruction of high-resolution X-ray computed tomography data showing cranium and mandibles of C. fulleri
Kamei, R.G., San Mauro, D., Gower, D.J., Van Bocxlaer, I., Sherratt, E., Thomas, A., Babu. S., Bossuyt, S., Wilkinson, M. and Biju, S. D. 2012. Discovery of a new family of amphibians from northeast India with ancient links to Africa. Proceedings of the Royal Society B: 1-6. doi:10.1098/rspb.2012.0150.
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