| abstract | We found four species of oribatid mites belonging to family Oppiidae from Babeldaob Island of Palau Republic, which is an island country located in the western Pacific Ocean. Two new species, Anomaloppia babeldaobensis sp. nov. and Oxyoppia palauensis sp. nov. are described from litter and soil in a secondary forest of Palau, and supplementary descriptions of two hitherto known species, Arcoppia corniculifera (Mahunka 1978) and Arcoppia hammerae Rodríguez & Subías, 1984 are provided, which are reported for the first time from the Oceania region. Following the descriptions and comparisons, aspects of the taxonomy, distribution and habitat ecology of studied species are discussed. |