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Remarkably higher species diversity of the rare symbiotic shrimp genus Onycocaridella inhabiting marine sponges is recorded from Papua New Guinea (PNG). Although only three species have previously been known from the whole Indo-West Pacific, the molecular revision recovered the presence of four yet unknown species even from limited series of specimens from a single geographic region, PNG. Three of the new species are described in the present study, two of the examined species are newly reported also from Australia and New Caledonia. The application of complementary collecting techniques (hand picking, stone brushing, dead-coral sorting, suction sampling) together with molecular analysis of obtained exemplars may allow more substantial insight into the real diversity of rare macrozoobenthic marine organisms.