Abstract:A new species of slipper lobster, Petrarctus holthuisi, new species, is found from the recent expeditions to the Philippines and Vanuatu. The new species resembles P. rugosus (H. Milne Edwards, 1837) but has a different colouration and several morphological differences. Comparisons of the partial sequence of cytochrome c oxidase subunit I (COI) show high degree of divergence (12.5-22.3%) among all the species of Petrarctus. The molecular genetic analysis also suggests that the recent separation of Scyllarus sensu lato may need to be revised. A key to all Petrarctus species is provided.