Professor SD Biju from Delhi University (DU) and his team discovered four new miniature species.
This is now listed among the smallest known frogs in the world.
The scientists were surprised by the relative abundance of these new miniature species.
In all Biju's team have discovered seven new frog species belonging to the genus Nyctibatrachus, commonly known as Night Frogs.
This finding is a result of five years of extensive explorations in the Western Ghats global biodiversity hotspot in India.
Four out of seven of the new species are miniature-sized frogs (12.2-15.4 mm), which can sit on a coin or a thumbnail.
These are among the smallest known frogs in the world.
Unlike other frogs in the genus that are predominantly stream dwelling, the new miniature frogs were found under damp forest leaf litter or marsh vegetation.
The newly sampled frogs were confirmed as new species by using an integrated taxonomic approach that included DNA studies, detailed morphological comparisons and bioacoustics.
Earlier Night Frog genus comprised of 28 recognized species of which only three were miniature-sized (<18mm).
Now the total number of known Nyctibatrachus species has increased to 35, of which 20% are diminutive in size.
This frog genus is endemic to the Western Ghats of India and represents an ancient group of frogs that diversified on the Indian landmass approximately 70-80 million years ago.
Among the new species are four true miniatures, between 10 and 15 mm body length, among the smallest of frogs.
These seem to be common locally and they probably were overlooked because of their small size.
They occur more terrestrially, in leaf litter.
However, the future of many of the new species may be bleak. All the newly described species are currently known only from single localities in the southern Western Ghats, and some lie outside protected areas.
Researchers found the Radcliffe's Night frog and the Kadalar Night Frog inside private or state-owned plantation areas facing threats such as habitat disturbance, modification and fragmentation.
The Athirappilly Night Frog was found in close vicinity to the Athirappilly waterfalls and the Sabarimala Night Frog near the Sabarimala pilgrimage centre, both of which are disturbed by anthropogenic activities.
"Over 32%, that is one-third of the Western Ghats frogs are already threatened with extinction.
Western Ghats: Know More- Elevation: 2,695 m
- Area: 160,000 km²
- Highest point: Anamudi
- Passes: Tamhini Ghat, Naneghat, Palakkad Gap, Kasara ghat
- Types of rock: Basalt, Limestone
