A new marine gastropod species of the genus Trapania Pruvot-Fol, 1931, is described from Cabo Blanco, Puntarenas, Costa Rica and from Islas Secas, Panamá. Trapania inbiolica sp. nov. has a white body with red patches, white rhinophores with sorne liule red patches, yellow appendages with partially red bases. The radula is composed of 28 rows of teeth. Each tooth has a large conical cusp with 21-24 denticlcs. Two or three of those denticles on the inner side of the eusp are smaller than the others. There are also 1-3 small denticles on the outside of the cusp. The jaw elements are very irregular
Keywords: mollusca, opisthobranchia, nudibranehia, goniodorididae, trapania, costa rica, panamá, pacific oecan