Nematogens and vermiform embryos of a new species of Dicyema are described from an octopus collected off Veracruz, México. Dicyema shorti n. sp. is a small dicyemid species that rarely exceeds 500 μm in length. It is further characterized by the presence of 18 peripheral cells in the vermiform stages, a conical-shape calotte, and an axial cell that extends to the base of the propolar cells. Other stages in the life cycle of the parasite are not known. This is the first dicyemid to be described from Octopus burryi Voss, 1950, and also from both the southern Gulf of Mexico and the country of México.