Legless amphibians discovered
New Delhi, Feb 22, 2012, DHNS: 23:50 IST
Scientists have discovered a new member of the vertebrate family, a worm-like legless amphibian, in the northeast, which surprisingly has a strong African lineage.
The discovery of new family of vertebrate (animals with backbone including human beings) amphibian is a rare feat and achieved after digging 250 localities in seven northeastern states, Sikkim and Darjeeling district of West Bengal over five years between 2006 and 2010. They are called caecilians.
The new family of tailless burrowing caecilians was described based on differences in external and internal appearance compared to the nine families of legless amphibians. The scientists performed DNA analysis of the specimens and confirmed that it is an entirely new family.
“These caecilians are one of the first land animals to be evolved on earth millions of years ago even before the frogs. They are significant to improve our understanding of the evolution,” S D Biju from Delhi University who led a team of field biologists from India, UK and Belgium for the survey, told Deccan Herald.
The new family has been named Chikilidae and the new genus as Chikila. The scientific name Chikilidae was derived from a Garo (a northeast Indian tribal) word for caecilians. The discovery has been reported in the Proceedings of Royal Society of London on Wednesday.
Most of the world’s 61 amphibian families were described in the mid-1800s and majority of new discoveries come from remote tropical rainforests. Except another frog family described by the same DU group in 2003, no other new family of vertebrates were found in India in the last 100 years.
Based on DNA evidence, researchers estimate that the new tailless burrowing caecilians evolved separately from other species of caecilians more than 140 million years ago. The new family is an ancient lineage whose closest relatives occur in Africa, a relationship established before the break up of the southern continents (Gondwana).
“The African lineage is the most surprising factor. No other Indian species show such strong lineage with Africa as Indian species are more closely linked to South Asia,” Biju said.
Chikilidae is a group of extremely dedicated burrowers, which exhibit an intriguing and highly specialised reproductive behaviour.They are among the keystone species for the ecology and improves soil health.
The mother builds underground nests for her eggs, guards her egg-clutch by coiling around them until the embryos hatch that takes about 2-3 months. The eggs undergo direct development – they feed on the yolk reserves and come out as miniature adults without an intervening free-swimming larval stage that is generally characteristic of amphibians.