BACKGROUND: Ligophorus Euzet and Suriano, 1977 is a specious genus of ancyrocephalid monogeneans parasitizing mullets around the world, with most species distributed in the western Pacific and the Mediterranean Sea. Only nine out of the 62 species in the genus have been reported from the Americas, and from them, only two have been sequenced. METHODS: We analyzed two species of Mugil (L.) from Northern Yucatán Peninsula. Specimens of Ligophorus were sampled from the gills of their hosts. The morphology of the specimens was examined. In addition, 28S and ITS rDNA sequences were obtained and compared with previous sequences downloaded from GenBank. RESULTS: We discovered two species of Ligophorus using morphological and molecular characters, L. mediterraneus, parasitizing the stripped mullet Mugil cephalus off the coast of Celestún, and L. yucatanensis, parasitizing the silver mullet M. curema in four coastal lagoons. Sequence data of the latter species are reported for the first time. CONCLUSION: Our findings showed that two species of Ligophorus occur in mugilids of the Yucatán Peninsula. One represents a widely distributed marine species with records in the Mediterranean Sea and the Yucatán Peninsula, whereas the second one, L. yucatanensis, represents an endemic species restricted to coastal lagoons of the Yucatán Peninsula.