First record of the Phoenix Islands damselfish Plectroglyphidodon phoenixensis (Schultz, 1943) from the Northwestern Hawaiian Islands

Abstract

Background: The coral reef fishes of Northwestern Hawaiian Islands (NWHI), encompassed by the Papahanaumokuakea Marine National Monument (PMNM), are known for high levels of endemism, as well as for strong affinities to the biota of Johnston Atoll. A novel species of pomacentrid damselfish, Plectroglyphidodon phoenixensis, is recorded for the first time from the NWHI. Results: A total of nine individuals of Plectroglyphidodon phoenixensis were recorded at French Frigate Shoals in September 2017. All observations were made by skin divers in shallow (< 1 m), extremely surgy rocky subtidal habitats. These observations represent a significant range extension of this species into the north central Pacific. No individuals of P. phoenixensis were observed in similar surgy rocky subtidal habitats at the adjacent islands of Nihoa and Mokumanamana. Conclusion: The discovery of multiple P. phoenixensis in an under-sampled habitat suggests that they may occur in Hawai'i more frequently than was previously thought. These observations provide valuable information on the habitat preferences and geographic range of this species. Given the absence of a reproducing population in the Hawaiian Archipelago, the closest source of propagules of this species is Johnston Atoll.