Taxonomy and biogeography of the coastal fishes of Juan Fernandez Archipelago and Desventuradas Islands, Chile

The Desventuradas Islands (San Felix and San Ambrosio) and Juan Fernandez Archipelago (Robinson Crusoe and Alejandro Selkirk) are oceanic islands of volcanic origin located in the southeastern Pacific off Chile. Based on new material collected since 1997, revision of the R/V Anton Bruun expeditions collections, and a taxonomic update, the coastal fish fauna of Juan Fernandez Archipelago and Desventuradas Islands found a total of 52 species, with 41 and 43 species, respectively. The number of coastal fish species recorded herein as endemic for Juan Fernandez is only five (12,2%) and three species are new records (Gymnothorax cf. obesus, Gnathophis sp., Suezichthys sp). The Desventuradas Islands have only two endemic species (4,6%) and four species are new records (Scorpaenodes englerti, Maxillicosta reticulata, Suezichthys sp., Aseraggodes bahamondei). The reduced number of endemic species for the Juan Fernandez Islands as compared with previous accounts (15 species) is the result that more species were found to be endemic to both islands groups (22 species = 42,3% all coastal fishes), suggesting these two island groups should be considered a single biogeographic unit. The eastern extension of the Indo West Pacific Region to include the Nazca Ridge, Desventuradas and Juan Fernandez Islands is supported herein. The zoogeographical affinities between Desventuradas and western Pacific Islands (Easter Island to Australia), includes 16 species, adding five new species to previous lists. Relationships of three genera indicate a Western Pacific origin with one or more dispersal events to the Desventuradas and Juan Fernandez Islands. Another seven genera, with relatively few species and restricted distribution, may have this same pattern. Only one phylogenetic study indicates a continental origin with a westward dispersal (Odontesthes), however another three genera may have this same pattern of dispersal.