A taxonomic approach with DNA studies and morphological comparisons was used to confirm them.
Scientists exploring the forests of the Western Ghats have come across four new species of tiny frogs no bigger than a human thumbnail, which make a distinctive chirping sound comparable to that of a cricket.
These species are among the seven new ‘Night Frogs’ discovered by a team of researchers from the University of Delhi and the Kerala Forest Department, who spent five years surveying the global biodiversity hotspot.
Night Frogs belong to the Nyctibatrachus genus endemic to the Western Ghats and represent an ancient group of frogs that diversified on the Indian landmass approximately 70 to 80 million years ago.
The scientists were surprised by the relative abundance of the previously unknown species at their collection localities.
“The minuscule frogs have probably been overlooked because of their extremely small size, secretive habitats and cricket-like calls,” says Sonali Garg who undertook the study as part of her Ph.D research at the University of Delhi.
The scientists used an integrated taxonomic approach that included DNA studies, detailed morphological comparisons and bioacoustics to confirm the new species. The findings have been published in the latest issue of PeerJ , an open access journal.
While turning the spotlight on the amphibian diversity of the Western Ghats, the discovery also highlights the threat posed by human activities to the species.
The Athirappilly Night Frog was found close to the Athirappilly waterfalls, the proposed site of a hydroelectric project, while the Sabarimala Night Frog was discovered near the hill shrine which receives lakhs of pilgrims every year. The Radcliffe’s Night frog and the Kadalar Night Frog were reported from plantation areas.
“Over 32% of the frog species in the Western Ghats are already threatened with extinction. Out of the seven new species, five face considerable anthropogenic threats and require immediate conservation,” says Prof. S.D Biju, who led the study and has formally described over 80 new species of amphibians from India.
“Because several of the new species have been identified as being range-restricted and impacted by threats, it is important to assess their extinction risks and tailor conservation strategies for both species and habitats,” said Ariadne Angulo, co-Chair, Amphibian Specialist Group, IUCN, in an emailed response.
The discovery has taken the total number of known Nyctibatrachus species to 35, of which 20% are diminutive in size (less than 18 mm).
As many as 103 new amphibian species have been described from biodiversity- rich Western Ghats region between 2006 and 2015.