Werding, B., Hiller, A., and Lemaitre, R. 2003. Geographic and distributional patterns of western Atlantic Porcellanidae (Crustacea: Decapoda: Anomura), with an updated list of species. In: Lemaitre, R., and Tudge, C.C. (eds), Biology of the Anomura. Proceedings of a symposium at the Fifth International Crustacean Congress, Melbourne, Australia, 9‐13 July 2001. Memoirs of Museum Victoria 60(1): 79‐85. Information on horizontal and vertical distributions of all known western Atlantic species of Porcellanidae is summarised, and an updated list of the 48 currently valid species is presented. The distributions and zoogeographic affinities of the group are discussed. In the western Atlantic, the Caribbean-West Indies region is the richest in number of species with 43, of which 40 species occur in the southern Caribbean. Species numbers decrease towards the peripheral regions of Florida, with 17 species, and Brazil, with 19 species (including two endemics). The Caribbean-West Indies porcellanid fauna shares 17 species with tropical Florida and 17 with tropical Brazil. There is a clear similarity in species composition between the tropical faunas of Florida and Brazil, sharing 11 species. Based on depth ranges, the species can be divided into “intertidal” (range ≤ 7 m) and “sublittoral” (range > 7 m) species. A relationship was observed between depth distributions and geographic ranges of western Atlantic porcellanids: “sublittoral’ species have wide geographic ranges, presumably as result of greater dispersal potential and ability to colonise a variety of ecological habitats; “intertidal” species have narrow geographic ranges, presumably as result of lower dispersal ability and narrow ecological requirements. For western Atlantic porcellanids, the Amazon River delta and the Florida Current are dispersal barriers more effective for “intertidal” than for “sublittoral” species.