Hyperiid Amphipods (Crustacea: Peracarida) in Mexican Waters of the Pacific Ocean

Information on regional diversity of hyperiid amphipods of the eastern Pacific Ocean is still largely incomplete. Recent surveys of hyperiid fauna from the Mexican Pacific motivated a revision of extant faunistic accounts. This revised list includes all records from Mexican waters of the eastern Pacific (MP) from Baja California to the southern border with Central America. A total of 150 species belonging to 19 families and 48 genera of the Hyperiidea was included in this account; seven are new records in the MP. Up to 31 nominal species were excluded from previous listings. Overall, the epipelagic infraorder Physocephalata is highly diverse in the MP (119 species); Physosomata, containing deep-living forms, are less diverse (31 species). The northern part of the MP (including the gulf and off the Baja California peninsula) harbors the highest number of species/records, whereas nearly half of the species are known from the central areas and six from the southernmost sector of the MP. This pattern reflects current knowledge of the group in these areas and also geographic differences in the sampling/research efforts, but it is not a diversity gradient. Species richness of the MP is comparable with that known from other Pacific subregions. The epipelagic hyperiid fauna of the tropical MP remains relatively unknown and should be studied further to reveal regional patterns of diversity. The deep-living hyperiid community of the tropical eastern Pacific harbors a diversity that is deserving of further study.