Abstract
The Fiji archipelago harbours a surprisingly diverse and endemic ant fauna, despite its isolated and remote location in the South Pacific. The ant genus Proceratium is present on Fiji with three endemic species, of which Proceratiumoceanicum De Andrade, 2003 and Proceratiumrelictum Mann, 1921 were previously known. In this study we describe the third species: Proceratiumvinaka sp. n. All three species are members of the widespread and species-rich Proceratiumsilaceum clade. In order to integrate the new species into the current taxonomic system, we present an illustrated identification key to the worker caste of the three Fijian species. In addition, we provide a detailed description of Proceratiumvinaka, as well as species accounts for the other two species, which include diagnoses, taxonomic discussions, specimen photographs, and a distribution map.