Scientists in London have identified two new species of giant salamander – and they think one of them may be the world's biggest amphibian. 

The Chinese giant salamander, which is critically endangered, was considered a single species until researchers at the Zoological Society Of London (ZSL) and the Natural History Museum examined DNA from various salamanders – including museum specimens collected nearly 100 years ago. 

The notion of a separate South China giant salamander had been proposed before, but only now has evidence been found for three distinct genetic lineages, using a salamander that was preserved after living at London Zoo in the 1920s.

The South China species is believed to be the biggest of the three – and as the Chinese giant salamander is already the world's largest amphibian, that would make the new discovery the largest of the 8,000 or so amphibian species. Scientists believe it could grow to almost two meters long.

"Our analysis reveals that Chinese giant salamander species diverged between 3.1 and 2.4 million years ago," said Samuel Turvey of the ZSL. "These dates correspond to a period of mountain formation in China as the Tibetan Plateau rose rapidly, which could have isolated giant salamander populations and led to the evolution of distinct species in different landscapes."

The other new species, which is yet to be formally described or named, comes from the Huangshan (Yellow Mountain) range in Anhui Province, eastern China.

The ZSL, which works in China to protect endangered giant salamanders in the wild, also raises awareness via an exhibit at London Zoo. In September 2016, four juvenile giant salamanders being illegally imported were seized by the UK Border Force and turned over to London Zoo, where one of them – called Professor Lew – now lives in the Reptile House. It is hoped he will be provided with a potential mate when he reaches maturity, as scientists strive to understand more about this mysterious species. 

^{(Video credit: ZSL)}