First viviparous Asian amphibian
doi:10.1038/nindia.2008.253 Published online 31 July 2008
In the first Asian report of an amphibian species nurturing embryos inside the body and then giving birth to offsprings, researchers have discovered four foetuses inside a female Geogeneophis seshachari, one of the smallest known worm-like amphibians (caecilians)1.
The phenomenon called viviparity was observed in a gravid female containing four foetuses in its oviduct, the passage from the ovaries leading outside the body.
The Indo-British study revealed that viviparity has evolved independently at least four times within this type of animal. The oviducts were highly vascularized and contained patches of thickened, layered tissue similar to foetal gut contents. The researchers point out that the species resembled other viviparous caecilians in having foetuses that consume thick oviduct lining using special teeth.
Gegeneophis is the only caecilian genus known to have oviparous and viviparous species, and G. seshachari is the smallest known viviparous caecilian. The researchers carried out phylogenetic analysis of the mitochondrial DNA sequences to find that it had evolved from a single common ancestral form. They contend that more attention should be focused in studying caecilian reproduction.
The authors of this work are from: Department of Zoology, The Natural History Museum, London, UK; Bombay Natural History Society, Mumbai, India and National Centre for Cell Science, Pune University Campus, Pune, India.
- Gower, D. J. et al. Frequency of independent origins of viviparity among caecilians (Gymnophiona): evidence from the first 'live-bearing' Asian amphibian. J. Evol. Biol. doi: 10.1111/j.1420-9101.2008.01577.x (2008)