India, Feb. 5 -- Amphibians, one of the most imperiled groups of life forms on the planet, have now officially reached 9,000 described species, according to a new research paper.

Amphibians reach 9,000 described species: a summary of ongoing trends, challenges, and opportunities by Sky T Button, Franco Andreone, and Amael Borzee, notes that "this benchmark in described species represents a major milestone for both taxonomy and conservation, resulting from thousands of individual studies conducted by countless amphibian research teams".

According to the authors, the number of recognised amphibian species has more than doubled within the past 40 years, and the number of annual new species descriptions appears to have peaked only recently,...