In an exciting development for India’s biodiversity, researchers have announced the discovery of an entirely new genus and species of freshwater crab! This remarkable find comes from the picturesque Shevaroy Hills in Yercaud, Salem district, further enriching our understanding of the country’s diverse crustacean life.
Meet Patithelphusa, the newly identified genus, and its first-known species, Patithelphusa yercaudensis. This discovery was made during a collaborative zoological survey involving experts from the Zoological Survey of India (ZSI) in Kolkata and Pukyong National University in South Korea. The dedicated research team was spearheaded by Santanu Mitra and Shibananda Rath from the ZSI, alongside Hyun-Woo Kim and Shantanu Kundu.
The genus name, Patithelphusa, pays homage to Sameer Kumar Pati, a distinguished Indian taxonomist celebrated for his substantial contributions to freshwater crab research.
These fascinating creatures were found nestled in a muddy microhabitat next to a rocky stream in Manjakuttai, within the Shevaroy Hills, an area soaring over 1,400 meters above sea level. After collection, the specimens underwent meticulous preservation and examination at the ZSI’s Crustacea Division. Researchers conducted thorough morphological studies, complemented by advanced molecular analysis using mitochondrial DNA sequences, to ascertain their unique identity.
As detailed in the prestigious international zoological journal ZooKeys, Patithelphusa yercaudensis stands out significantly, both genetically and morphologically, from its closest known relatives. Genetic analysis revealed a substantial 9.66% divergence from Travancoriana schirnerae, a species native to southern India. Visually, this new species is characterized by its broader carapace, distinctive triangular lobes, and unique male reproductive structures, setting it apart from other genera like Baratha, Vanni, and Vela.
Researchers hypothesize that the topographical isolation of the Shevaroy Hills played a crucial role in shaping this crab’s evolution. Separated from neighboring mountain ranges by deep valleys and the expansive Cauvery River system, these natural barriers likely limited gene flow, enabling crab populations to evolve distinctly over long periods. Such high-altitude enclaves within the Eastern Ghats are proving to be vital refuges for endemic species uniquely adapted to their specialized surroundings.
This discovery vividly underscores the ecological importance of the Eastern Ghats. Despite being a treasure trove of biodiversity, this region remains considerably less explored compared to its Western Ghats counterpart. The researchers emphasize that the full spectrum of freshwater crab diversity across the Indian subcontinent is continually being revealed, with numerous species currently known only from very localized habitats.
With the addition of Patithelphusa yercaudensis, India’s recorded freshwater crab species count now reaches 112, spanning 31 genera within the Gecarcinucidae family. Remarkably, India is home to nearly 10% of the world’s total known freshwater crab species, many of which are confined to small, specific habitats, highlighting their vulnerability and unique adaptations.
The study’s authors stress the urgent need for ongoing surveys and thorough documentation to fully comprehend the rich diversity of freshwater crabs throughout peninsular India. Furthermore, they highlight the critical importance of protecting these delicate hill-stream ecosystems, which are increasingly threatened by mounting pressures from tourism and evolving land-use practices in areas like Yercaud.