Taxonomic Composition, Distribution and Zooeoahic Relationships of the Grapsid and Ocypodid Crab Fauna of Intertidal Soft Bottoms in the Arabian Gulf

Abstract

Brachyuran decapods of the families Grapsidae and Ocypodidae are a dominant faunal element of intertidal flats and mangroves in the Arabian Gulf and the Gulf of Oman. Recent collections along the coasts of the U.A.E. and Saudi Arabia and examination of material from other parts of the Gulf revealed in total six species of grapsid and 21 taxa (species and subspecies) of ocypodid crabs occurring in these habitats within the Arabian Gulf. Great differences in species diversity and composition exist between the different parts of the Arabian Gulf. Maximum diversity was observed for the easternmost part of the U.A.E. (Ras al Khaimah, Umm al Quwain) and for Kuwait. Highly reduced species numbers were found along the shorelines of Abu Dhabi and Saudi Arabia. The most likely factor causing this pattern is salinity. Zoogeographically it appears, that most of the Arabian Gulf species are of an ‘eastern’ (Indian) origin. ‘Western’ (East African and Red Sea) elements are restricted to the south-eastern part of the Gulf (coast of the U.A.E.) and to the Gulf of Oman.