Acanthurus nigros is not a ‘new’ species but yet it has now been resurrected to name a gentically distinct yet identical-looking species to Acanthurus nigroris. Acanhturus nigros is the name that was originally used for the Bluelined Surgeonfish when it was first described back in 1853. Over a hundred years later Jack Randall revised the genus Acnathurus and lumped together A. nigroris and A. nigros into the same species. Fast-forward to 2010 and genetic analysis of the Pacific Blueline surgeonfish, A. nigroris, revealed that the species was very well connected throughout the West and South Pacific Ocean, but that a very distinct species occurs in the Hawaiian archipelago.
Following the results of the genetic tests, Jack Randall went back and re-analyzed specimens of A. nigroris from all over the Pacific Ocean and was able to find differences in gill rakers and fin ray counts but the two species are identical in their appearance. Unlike Centropyge deboraie we doubt the hobby will pay much attention to the re-description of a cryptic species but now you know: bluelined surgeonfish from Hawaii are A. nigroris and those from everywhere else are A. nigros.