Three new species of the sea fan genus (Cnidaria, Octocorallia, Plexauridae) from the northwest region of Mexico.

Twenty-one nominal species of have been reported in the Eastern Pacific with nine of them reported in the Mexican Pacific. We describe three new species of and , from rocky reefs on the central and the northern Gulf of California and the Pacific coast of Baja California Sur, and , from the Pacific coast of Baja California Sur. and are taxonomically allied to the nominal species Verrill, 1869 due to the morphological similarity of colony growth patterns and the phylogenetic closeness based on the mitochondrial MutS gene (mtMutS); but differ mainly in the calyx form and composition of sclerites. The main morphological differences between the new species are in their sclerite forms and color; has orange-colored colonies, thin leaf spindles and tuberculated blunt spindles, while has dark brown colored colonies, strong spinous spindles and an absence of tuberculated blunt spindles. is phylogenetically close and morphologically similar to Verrill, 1869 in the growth form of the colony and tubular calyces; but has dark brown colored colonies and has calyces from the base to the branch tips. With these three new species, the total number of species reported in the Mexican northwest region increases to twelve and a total of 24 nominal species in the Eastern Pacific.