Pharaxonotha portophylla, new species (Insecta: Coleoptera: Erotylidae: Pharaxonothinae), is described based on individuals collected on the cones of native populations of Zamia amblyphyllidia D. W. Stevenson and Z. portoricensis Urban (Cycadales: Zamiaceae) in the Puerto Rican Cambalache and Susúa Commonwealth Forests, respectively. The new species is a member of a complex centered around P. floridana (Casey), and may be distinguished from other Pharaxonotha species by the following traits: head lacking supraocular striae, with coarse punctation; pronotum slightly transverse, anterolateral edges weakly projected and angulate; protibia narrowly triangularly widened toward apex; elytra with an anterior marginal line, elytral punctures coarse, not impressed, elytral striae not grooved, and elytral intervals plane. Pharaxonotha portophylla is the second species in this genus reported for the Caribbean region, raising the number of known Pharaxonotha species to 13 worldwide. Samples of insect visitors on Zamia cones of either gender and at various stages of anthesis strongly suggest that P. portophylla is the primary and sole pollinator of these cycad species at the two locations. The abundance of adult individuals was much lower on the receptive megastrobili than on the pollen-releasing microstrobili which produced similar attracting odors. Larval development was restricted to the microstrobili, possibly indicating the presence of defensive metabolites in the megastrobili and a reproductive interaction with “pollination by deceit”.