Thirty-eight species of xanthoid crab are recorded for the first time from Dhofar Province, southern Oman. The geographical range of three species[Nanocassiope alcocki(Rathbun 1902),Actumnus digitalis(Rathbun 1907), andMacromedaeus crassimanus(A. Milne Edwards 1867)] is substantially extended. The pattern of xanthoid species diversity is discussed in relation to the effect of the seasonal monsoon-driven upwelling, and compared with that of other parts of the Western Indian Ocean.