The species is endemic to the Western Ghats mountain range of India, where it is found in Kerala, Tamil Nadu, and Karnataka.

Adults inhabit fast-moving forest streams at elevations of up to 900 m (3,000 ft) and have highly specific habitat requirements.

The species is currently classified as being vulnerable on the IUCN Red List owing to its small and fragmented range and ongoing habitat degradation.

Threats to the species include habitat loss, increased human presence near the streams it inhabits, and possibly nitrate pollution caused by fertiliser overuse.

[8][9] This species was synonymised with N. major by the herpetologist Raghavan Pillai in 1978, as he found the shape of the pupil to be a variable characteristic in preserved specimens.

[7] According to a 2017 study by the herpetologist Sonali Garg and colleagues, within the genus, it is sister (most closely related) to a clade (group of organisms descending from a common ancestor) formed by N. acanthodermis and N. gavi.

[12] The following cladogram shows relationships within this clade based on a phylogeny from the 2017 study by Sonali Garg and colleagues:[10] N. indraneili N. radcliffei N. grandis N. sylvaticus N. acanthodermis N. gavi N. major The species had its DNA barcoded in 2010.

This barcoding allows unknown specimens of the frog to be identified accurately with even small tissue samples, which could help resolve taxonomic uncertainties and aid conservation efforts for the species.

The development of species-specific microsatellite markers could offer tools for assessing genetic variation and population dynamics, further informing conservation strategies for this species.

The colour of the band between the eyelids changes to faint grey, and the underside and sides become whitish, the latter marked with black spots.

After reaching a length of 1.5–1.9 cm (0.59–0.75 in), tadpoles have only a tail stump and begin metamorphosing; they can be distinguished from adults by the lack of grooves on the fingers.

[16] The species is endemic to the Western Ghats of southern India, where it is found in Kerala, Tamil Nadu, and Karnataka.

[21] Nyctibatrachus major is classified as being vulnerable on the IUCN Red List due to its small and fragmented range and ongoing habitat degradation.

[1] It is threatened by habitat loss caused by factors such as deforestation, wood and timber harvesting, and conversion of land for agricultural use.

[17][18] Consequently, increased human activities that alter their habitat may lead to declines in the species' population, as has occurred in the related N.

Due to habitat fragmentation, many of the streams the frog inhabits are adjacent to farms that experience high levels of nitrogen-based fertilizer use, leading to elevated nitrate concentrations in the water.

Even sub-lethal concentrations of nitrates in the water lead to adverse effects such as paralysis, restlessness, abnormal swimming patterns, and swollen body parts.