New species of tree living crab found in Western Ghats

by Oxford University Press

A Kani maranjandu crab. Credit: Authors

A recent research paper in The Journal of Crustacean Biology reveals a new genus and new species of tree crab in Kerala, southern India. Known scientifically as the "Kani maranjandu," it is substantially different from other congeners. Its distinguishing characters include: the structure of its hard upper shell, as well as its male abdominal structure and reproductive parts, and of course, its diagnostic elongated walking legs, which no other genus has. (see fig 1).

The Western Ghats in India is a biodiversity hot spot for plants and animals. However, its freshwater biodiversity, especially with regard to crabs, remains poorly documented. This is the first report of its kind to offer a record of an arboreal crab—a crab species that lives in trees.

During a two year survey of the freshwater crab fauna, which started in 2014 in Westerns Ghats in Kerala, India, the people of Kanikkaran (also known as Kani) reported sightings to the survey team of "long-legged" tree crabs in the area. Early attempts to capture them proved futile. On September, 5 2016, researchers with the help of the Kani tribe were finally able to capture a female specimen and later a large adult male. (see fig 2).

The specimens examined are deposited in the Zoological Survey of India and in the museum collection of the Department of Aquatic Biology and Fisheries, University of Kerala, India. The new species is named "Kani maranjandu" after the Kani tribe in Kerala, who helped discover the tree crab. Maranjandu is the local Malayanam name for tree crab.

According to Dr. Biju Kumar, one of the study's authors, the discovery of this crab is very important in the context of conservation of the Western Ghats Biodiversity Hotpot as they can serve as ecological indicators, reflecting the health of the ecosystem. "As water holding hollows in large trees are essential for the survival of this unique species, the discovery also stress the need for conservation of large trees in the degraded forest ecosystems of the Western Ghats," Kumar said. "It also highlights how little we know about the actual biodiversity that resides in these forests and the efforts that must still be made to find and study the many undoubted new species that still live there."