Brachyuran Diversity in Coastal Ecosystems of Tamil Nadu

Diversity of brachyuran crabs of coastal ecosystems of Tamil Nadu is documented and critically analysed. The crabs reported so far from these ecosystems comprise of 344 species belonging to 154 genera under 23 families. Highest diversity of species has been observed at Gulf of Mannar (195 species) followed by Chennai coast (169 species), Palk Bay (98 species) and Parangipettai coast (84 species), while highest diversity of species has been encountered in the family Xanthidae (56 species) followed by Portunidae (53 species), Leucosidae (41 species), Majidae (36 species), Grapsidae (32 species) and Ocypodidae (19 species). Zoogeographical distribution of these species has been discussed along with endemicity. Amongst these crabs, 254 species are widely distributed in the Indo-Pacific region, 57 species are confined to the Indian Ocean and 25 species to Bay of Bengal. Habitat-wise distribution of 140 species of crabs has revealed the occurrence of 61 species in coral reef, followed by 40 species in mangroves, 23 species in backwater and 13 species in sandy habitats of this state. List of new taxa described so far from the state has also been given.