A new pentastomid, Porocephalus dominicana, from the Dominican boa (Constrictor constrictor nebulosus) is described. It differs in most aspects of its gross morphology from the other described Porocephalus spp. but it is included within the genus because it possesses the key generic character, an accessory spine over the outer hook. The taxon should be subdivided at the generic level if postulated differences in lifecycles can be demonstrated experimentally. ac]19790717