Three new records of Indo-West Pacific Littorinidae (Gastropoda) in the Tropical Eastern Pacific

Three species of Littorinidae that are widespread in the Indo-West Pacific (IWP) region are recorded from the Tropical Eastern Pacific (TEP) for the first time: Littoraria undulata (Gray, 1839) on Isla del Coco, L. coccinea (Gmelin, 1791) on Isla del Coco and Clipperton Atoll. and Peasiella conoidalis (Pease. 1868) on the mainland of Costa Rica. These are briefly described and figured. It is suggested that these may have been transported to the TEP as pelagic eggs or larvae, carried on the North Equatorial Countercurrent, perhaps during the enhanced flow characteristic of El Nino events. Records of IWP mollusks in the TEP are reviewed and reasons for the general lack of established populations of these species are discussed.