New fish species discovered in Periyar, ends 70-year scientific mix-up

A team of scientists has discovered a new fish species in Kerala’s Periyar Tiger Reserve and resolved a decades-old evolutionary mystery in the Western Ghats.

Published in the journal Systematics and Biodiversity, the study details the unexpected discovery of Eechathalakenda incognita, a new species of cyprinid fish belonging to the subfamily Torinae. Researchers described the fish from various streams inside the Periyar Tiger Reserve.

The find clears up 70 years of taxonomic confusion. The newly described species had been mistaken for its close relative Eechathalakenda ophicephala since the 1950s. Genetic and morphological analysis now shows they are distinct species.

Scientists used mitochondrial DNA sequencing and mapped the complete mitogenome to confirm the new species. E. incognita is visually distinct too — it has circular scales near the upper body and a dark lateral stripe, unlike the rhomboid-shaped scales of E. ophicephala. Genetic data also placed the entire genus firmly within the cyprinid subfamily Torinae, solving a long-standing puzzle about its evolutionary placement.

Both species have extremely restricted distribution and face habitat threats. E. incognita is found only in fast-flowing, rocky streams inside Periyar Tiger Reserve, while E. ophicephala is confined to headwaters of the Pamba river above 1,000 m. Because of their narrow range and threats from climate shifts and habitat degradation, researchers flag both as facing an extreme risk of extinction and an urgent priority for conservation.

The discovery marks E. incognita as the ninth point-endemic fish species identified within Periyar Tiger Reserve, reinforcing the reserve’s importance for freshwater fish conservation in Asia.