The Indian purple frog, Nasikabatrachus sahyadrensis, is a unique amphibian native to the Western Ghats of India. Its secretive, subterranean lifestyle has long shrouded it in mystery, making it a subject of scientific interest. This species represents a remarkable example of evolutionary divergence, remaining hidden from scientific discovery until recently.
Distinctive Features and Discovery
The Indian purple frog possesses a distinctive appearance, characterized by a plump, bloated body and a relatively small head with a pointed snout, which has earned it the nickname “pig-nosed frog”. Its skin typically ranges from dark purplish-brown to grayish. Adults usually grow to about 7-9 centimeters in length, with females often being three times larger than males.
The frog’s physical traits are specialized adaptations for its underground existence. Its short, muscular forelimbs and hard palms function like shovels, allowing it to efficiently burrow through soil. Unlike many frogs that leap, its unusually short hind legs mean it covers ground with long strides.
This species was formally described in 2003 by scientists S.D. Biju and Franky Bossuyt. Its discovery was significant due to its ancient lineage. The species is considered a “living fossil,” having evolved independently for approximately 120 million years. Its closest relatives, the Sooglossidae, are found over 3,000 miles away in the Seychelles islands, providing biological evidence for the ancient supercontinent Gondwana.
Habitat and Behavior
The Indian purple frog primarily inhabits deep underground environments within the Western Ghats mountain range, specifically in the states of Kerala and Tamil Nadu. It prefers loose, damp, and well-aerated lateritic soil, typically found at elevations between 450 and 1,200 meters above sea level. This fossorial (burrowing) lifestyle means it spends nearly its entire life beneath the soil.
The frog’s diet consists mainly of termites, which it hunts underground using its specialized tongue and a unique buccal groove. Its emergence from its subterranean world is brief, occurring only for a few hours to a few days each year during the monsoon season for breeding. Males emit unique calls from their burrows to attract females, which some describe as resembling a “chicken” sound. Females lay eggs in concealed crevices or under rocks in fast-flowing streams, and the tadpoles develop for about 100 days, clinging to stream bedrocks with specialized sucker-like mouths to withstand strong currents.
Conservation Status and Importance
The Indian purple frog is currently listed as “Endangered” on the IUCN Red List, reflecting the significant threats it faces. A primary threat is habitat loss, driven by the expansion of agriculture for crops like coffee, cardamom, and ginger, as well as deforestation and human development in the Western Ghats. Many of its specific breeding sites fall outside protected areas, making them vulnerable to these pressures.
The construction of check dams to control monsoon floodwaters also poses a threat, as these structures can remove the seasonal streams necessary for tadpole development. Additionally, the harvesting of tadpoles and adult frogs by local communities for food and traditional medicinal purposes contributes to population declines. The Indian purple frog’s conservation is important due to its evolutionary uniqueness as a relic species.