The tables have turned: taxonomy, systematics and biogeography of the Acropora hyacinthus (Scleractinia: Acroporidae) complex.

Genomic data have revealed that traditional coral taxonomy based on skeletal morphology does not accurately reflect the true diversity of, or systematic relationships within, the order Scleractinia. Here, we apply an integrated taxonomic approach combining molecular analysis and morphological comparison of type material with specimens collected from across the Indo-Pacific to revise the taxonomy of a clade within the species-rich and ecologically dominant reef coral genus Acropora , which includes the species Acropora hyacinthus (Dana, 1846) and related species (termed the 'hyacinthus species complex'). Using a collection of specimens comprising preserved tissues, field images and skeletal vouchers collected from 22 regions spanning the Indian and Pacific Oceans, we generated a phylogenomic reconstruction using targeted capture of ultraconserved elements (UCEs) and exons, combined with examination of morphological characters, to generate primary species hypotheses (PSHs) for the clade. We then tested PSHs by calling Single Nucleotide Polymorphism (SNPs) from the genomic dataset to provide additional lines of evidence to support the delineation of species within the clade and revise the taxonomy of the group. Our integrated approach recovered 16 lineages sufficiently delineated to be designated as distinct species. Based on comparison of our specimens to type material and geographical distributions, we remove nine species from synonymy: A. turbinata (Verrrill, 1864), A. surculosa (Dana, 1846), A. patella (Studer, 1878), A. flabelliformis (Milne-Edwards, 1860), A. conferta (Quelch, 1886), A pectinata (Brook, 1892), A. recumbens (Brook, 1892), A. sinensis (Brook, 1893) and A. bifurcata Nemenzo, 1971. We also describe five new species: A. harriottae sp. nov. from south-eastern Australia, A. tersa sp. nov. from eastern Australia and the Western Pacific, A. nyinggulu sp. nov. from the eastern Indian Ocean, Indo-Australian Archipelago and southern Japan, A. uogi sp. nov. from the western Pacific and A. kalindae sp. nov. from north-eastern Australia. Our data reveal that the species richness within this clade of Acropora is far greater than currently assumed due to both overlooked provincialism across the Indo-Pacific as well as lumping of distinct sympatric species based on superficial morphological similarity. Given the key ecological role tabular Acropora play on Indo-Pacific reefs our findings have significant implications for reef conservation and management, for example, A. harriottae sp. nov. is restricted to a small geographical region of south-eastern Australia and is therefore at comparatively high risk of extinction. ZooBank: urn:lsid:zoobank.org:pub:6C42546C-9253-4639-9FF4-D8D80808D78C.