Researchers have come across a new genus of freshwater crab with two new species from the Western Ghats region in Idukki district. The genus has been named Rajathelphusa after Rajakumari, the place where the specimens were spotted.
The discovery has been published in the latest issue of Zoological Studies by Smrithy Raj and A. Biju Kumar of the Department of Aquatic Biology and Fisheries, University of Kerala, and Prof. Peter Ng, head, Lee Kong Chian Natural History Museum, National University of Singapore, an authority on crabs. The two new species in the genus have been christened Rajathelphusa ala and Rajathelphusa muni . With their discovery, the number of freshwater crab species found in the Kerala part of the Western Ghats has risen to 39 and endemic species to 20, Prof. Biju Kumar, who heads the Department of Aquatic Biology and Fisheries, explained. ‘Ala’ alludes to the rock shelters used by the tribal people in the region, while ‘muni’ is Malayalam for hermit.
Near rivers
Both crab species — they are small enough to fit in the hand of an adult human — live in burrows near rivers. Rajathelphusa is endemic to Idukki, the researchers said.
Rajathelphusa ala is distinguished by a dark brown carapace with light brown chelipeds — the appendage with the claw — and ambulatory legs. Rajathelphusa muni has a reddish-brown carapace with yellowish-brown chelipeds and ambulatory legs. “The monsoonal climate of India is particularly suitable for terrestrial forest crabs such as Rajathelphusa , which need to keep their gills moist at all times. Their high carapaces allow them to have larger gill chambers that contain more water to help them respire, even during the dry season,” Prof Ng was quoted in a statement.
Fifty-nine species of freshwater crabs in the family Gecarcinucidae have been reported from the Western Ghats. They, however, remain poorly studied as many parts of the Ghats have not been surveyed for freshwater crabs, Prof. Kumar said.
