Indian scientists have discovered seven new frog species belonging to the genus Nyctibatrachus, commonly known as Night Frogs. This is an outcome 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 fit on a thumbnail or coin. These known to be the smallest frogs in the world.
Unlike other frogs in the genus that are predominantly stream dwelling, the newly found were found under damp forest leaf litter or marsh vegetation. Scientists were astonished by the relative abundance of these previously unknown species at their collection localities. “In fact, the miniature species are locally abundant and fairly common but they have probably been overlooked because of their extremely small size, secretive habitats and insect-like calls”, says Sonali Garg who undertook this study as part of her PhD research at University of Delhi.
A. Radcliffe’s Night Frog (Nyctibatrachus radcliffei) B. Athirappilly Night Frog (Nyctibatrachus athirappillyensis) C. Kadalar Night Frog , D. Sabarimala Night Frog E. Vijayan’s Night Frog F. Manalar Night Frog G. Robin Moore’s Night Frog (SD Biju) (Others)
The newly sampled frogs were confirmed as new species using DNA studies. Previously, the Night Frog genus comprised of 28 recognized species of which only three were miniature-sized (<18 mm). Now the total number of known Nyctibatrachus species has increased to 35, of which 20 percent 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.
The discovery of several new species of ancient origin can provide useful insights into the evolution of endemic frog lineages in the Western Ghats, which is a leading amphibian hotspot. The past decade has witnessed an exponential increase in the number of new amphibian species described from this region. Of the total new species of amphibians (1581) described globally between the years 2006–2015, the highest number were from the Brazilian Atlantic Forest (approximately 182) followed by the Western Ghats-Sri Lanka biodiversity hotspot (approximately 159), with 103 species described alone from the Western Ghats region.
12.2 mm long Robinmoore’s Night Frog (Nyctibatrachus robinmoorei) sittingon the Indian five-rupee coin (24 mm diameter) Photo by: SD Biju (Others)
However, the future of many of the new species may be bleak. All the newly found species are 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 proximity to the Athirappilly waterfalls and the Sabarimala Night Frog near the Sabarimala pilgrimage centre, both of which are disturbed by anthropogenic activities.
“Over 32 percent, that is one-third of the Western Ghats frogs are already threatened with extinction. Out of the seven new species, five are facing considerable anthropogenic threats and require immediate conservation prioritization”, says Prof SD Biju of Delhi University, who led the study.