A crustacean makes a belated appearance

Highlighting the rich aquatic biodiversity, new species of mangrove crab reported from Kasaragod

September 17, 2020 09:13 pm | Updated 09:15 pm IST - Thiruvananthapuram

Leptarma biju, the new species of mangrove crab discovered in Kasaraod.

Leptarma biju, the new species of mangrove crab discovered in Kasaraod.

Researchers from the National University of Singapore and the Department of Aquatic Biology and Fisheries, University of Kerala, have reported a new species of tree-spider crab from a mangrove forest in Kasaragod, highlighting the rich aquatic biodiversity in the mangrove ecosystem in Kerala.

Peter Ng, Head of the Lee Kong Chian Natural History Museum, National University of Singapore, and Suvarna S. Devi, Department of Aquatic Biology and Fisheries, University of Kerala, published their research in the latest issue of the international journal Crustaceana . The discovery is the outcome of the collaborative research between the institutions.

The new species is named Leptarma biju after A. Biju Kumar, Head, Department of Aquatic Biology and Fisheries, University of Kerala, for his support and contribution to research work on crustaceans in the State over the years. The discovery takes the number of mangrove-associated crabs in Kerala to 23. This is also the first report of the genus Leptarma from India.

The researchers collected three specimens of the new species from mangrove patches in the Chithari river mouth less than 100 m from the Arabian sea. The characteristic features of the new crab are its long ambulatory legs and short and hook-like dactylus (the tip of the digits) that have adapted the crustacean for tree-climbing.

The squarish external body cover (carapace) of the crab is light yellow with dark purplish patches, the ambulatory legs are light violet with reticulate patches, while the dactylus is light yellow. Another notable feature of the crab is its eye extending distinctly beyond the tip of the external orbital tooth.

“It is a bit surprising that no species of Leptarma has been recorded from India until the present discovery of this new crab, but this is probably due to the more nocturnal habits of many of the taxa,” said Prof. Peter Ng.

Noting that the mangrove forests in Kerala support extensive aquatic biodiversity, Prof. Biju Kumar said many regions remain poorly documented in terms of biodiversity and associated ecosystem services.

He called for special efforts for conservation of the few remaining tracts of healthy mangrove forests in northern Kerala, particularly in the districts of Kannur and Kasaragod.

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