The ant fauna of the Fijian archipelago is a diverse assemblage of endemic radiations, pan-Pacific species, and exotics introduced from around the world. Here we provide a taxonomic synopsis of the entire Fijian ant fauna by incorporating previously published information with the results of a recently completed, archipelago-wide biodiversity inventory. This synopsis updates the first and only other treatment of the fauna, W. M. Mann’s 1921 monograph, The Ants of the Fiji Islands. A total of 187 ant species representing 43 genera are recognized here. Of these species, 88% are native to the Pacific region, 70% are endemic to Fiji, and 12% are introduced into the Pacific region. Approximately 45 ant species in Fiji are undescribed, and are identified here by assigned code names. An illustrated key to genera, synopses of each species, keys to species of all genera, and a species list is provided. The work is further illustrated with specimen images, distribution maps, and habitat-elevation charts for all species. Seven taxa are promoted to full species status: Camponotus fijianus Özdikmen, stat. n., Camponotus kadi Mann stat. n., C. levuanus Mann stat. n., C. sadinus Mann stat. n., C. umbratilis Wheeler stat.n., Poecilomyrma myrmecodiae Mann stat. n., Romblonella liogaster (Santschi) stat. n. The following five taxa are revived from synonymy: Hypoponera eutrepta (Wilson) stat. rev., H. vitiensis (Mann) stat. rev., Monomorium vitiense (Mann) stat. rev., Paraparatrechina oceanica (Mann) stat. rev., N. vitiensis (Mann) stat. rev. The following new synonymies are proposed (senior synonym listed first): Camponotus cristatus Mann = C. cristatus nagasau Mann; C. kadi Mann = C. loloma Mann = C. trotteri Mann; C. polynesicus Emery = C. maudella Mann = C. maudella seemanni Mann = C. janussus Bolton; Pheidole knowlesi Mann = P. extensa Mann; Philidris nagasau (Mann) = P. alticola (Mann) = P. agnatus (Mann); Romblonella liogaster (Santschi) = R. vitiensis Smith, M. Lectotypes are designated for the following species: Camponotus vitiensis Mann, Gnamptogenys aterrima (Mann), Poecilomyrma senirewae Mann.

Invertebrates constitute the majority of animal species and are critical for ecosystem functioning and services. Nonetheless, global invertebrate biodiversity patterns and their congruences with vertebrates remain largely unknown. We resolve the first high-resolution (~20-km) global diversity map for a major invertebrate clade, ants, using biodiversity informatics, range modeling, and machine learning to synthesize existing knowledge and predict the distribution of undiscovered diversity. We find that ants and different vertebrate groups have distinct features in their patterns of richness and rarity, underscoring the need to consider a diversity of taxa in conservation. However, despite their phylogenetic and physiological divergence, ant distributions are not highly anomalous relative to variation among vertebrate clades. Furthermore, our models predict that rarity centers largely overlap (78%), suggesting that general forces shape endemism patterns across taxa. This raises confidence that conservation of areas important for small-ranged vertebrates will benefit invertebrates while providing a "treasure map" to guide future discovery.