In this paper the harpacticoidRaptolaophonte arduan.gen., n.sp., collected at Boddam Island (Chagos Islands) is described. The new genus is characterized by many features; in particular, the absence of sexual dimorphism in P2-P3 and the strong sexual dimorphism in P4 is noteworthy. Considering the related genera of Laophontidae as yet known, the new genusRaptolaophonteseems to have some affinities withLaophontinaNorman & Scott 1905 andIndolaophonteCottarelli et al. 1985. The new species is described and discussed in detail and further information on the samples sites are given.