On Decapoda Brachyura from the Andaman and Nicobar Islands – Families Portunidae, Ocypodidae, Grapsidae and Mictyridae.

Abstract

The present paper begins a series on the brachyuran fauna of the Andaman and Nicobar Islands, and describes 29 species and a variety collected during February to March 1960 from (1) Localities around Port Blair, viz. Bimbletan, South Point, Corbins Cove, Aberdeen Bay, Phoenix Bay, North Bay and Kalapahad ; (2) Neil! Island ; (3) Car Nicobar ; (4) Maya Bandar ; (5) Long Island ; and (6) Nancauri. Of these reported in this account, 8 species and 1 variety are recorded for the first time from this region. Heller (1868) recorded 27 species of crabs belonging to the three famiUes Portunidae, Ocypodidae, and Grapsidae. Alcock (1899 & 1900) in his ' Materials for a Carcinological Fauna of India' described 35 species of portunids, 13 species of ocypodids and 24 species of grapsoids from the Andaman and Nicobar Islands, apart from Mictyris longicarpus Latreille. Later de Man (1908-09) reported Sesarma thelxionae de Man ; Kemp (1919) Macrophthalmus pacificus Dana (=M. bicarinatus Heller) and Dotilla wichmanni de Man and Chopra (1931) Lissocarcinus ornatus Chopra from the same region. The collections were made mainly from the coral reefs and the intertidal region, vast areas of which get exposed during the ebb tide. A number of specimens were collected from the submerged reef with the help of a mask and snorkel. Portunids were mainly collected with a small dredge operated at 10 metres in the Aberdeen Bay, Port Blair.