ABSTRACT. – A new genus and species of the family Laophontidae, Carcinocaris serrichelata, is described and figured. This genus lives on the carapace of xanthid crabs collected in the intertidal zone along the coasts of some Philippine islands. Several laophontids have been reported as associates of xanthid crabs, however, Carcinocaris gen. nov. has several autapomorphies which distinguish it from them: maxilliped very well developed and ornate, forming an uncommon and efficient appendage involved in grasping the host’s hairs; P1 exopodite reduced to a short segment; P2 reduced to a small plate; P3 without endopodite and with two-segmented exopodite in both sexes; P4 very reduced, endopodite present only in females where it is reduced to a tubercle with one long seta. Several specimens of Xanthi - laophonte trispinosa Sewell were collected, which co-occurred on the same decapod host with Carcinocaris serrichelata sp. nov. Their morphology differed in few details from Fiers’ (1991) description. The Philippine records widen the species’ distribution in the Indian Ocean and adjacent seas.