Metabetaeus Borradaile, 1899 revisited, with description of a new marine species from French Polynesia (Crustacea: Decapoda: Alpheidae)

The alpheid shrimp genus Metabetaeus was previously known from two species associated with anchialine pools and caves, M. minutus (Whitelegge, 1897) and M. lohena Banner & Banner, 1960. In the present study, a somewhat unusual, coral reef inhabiting species of Metabetaeus, M. mcphersonae n. sp., is described based on one male and three female specimens collected off Moorea, Society Islands, French Polynesia. A detailed diagnosis of Metabetaeus is provided for the first time, accommodating characters of all three species. Distribution ranges are updated for M. minutus, recorded for the first time from Sulawesi and Christmas Island in the Indian Ocean, and for M. lohena, recorded for the first time from Rapa Nui (Easter Island). A key to the species of Metabetaeus is also provided.