Monogeneans in the northernmost Neotropical lake: unexplored species richness and freshwater fish host–parasite associations in Lake Catemaco

Abstract Lake Catemaco is a Neotropical volcanic lake in southern Mexico, which harbours several endemic and introduced fish species. The transfer of exotic monogeneans to native fishes was first documented in Mexico at Lake Catemaco: of eight monogenean species recorded in the early 2000s, four were introduced species. Twenty-five years later, we characterized monogeneans infecting 13 fish species from five families, with poeciliids and cichlids being the most species-rich fish families in Lake Catemaco. Members of Gyrodactylidea were both more abundant and more species rich than those of Dactylogyridea: we recovered 735 gyrodactylids corresponding to eight species of the genus Gyrodactylus plus four undescribed Gyrodactylus spp., in addition to members of the genera Anacanthocotyle, Scleroductus, and Ieredactylus affinis. From cichlids, we recovered 106 dactylogyrids, including only 5 specimens from the African genus Cichlidogyrus, suggesting that introduced monogeneans were not able to thrive in Lake Catemaco. Host–parasite associations show that most Gyrodactylidae are host specific: 11 species were associated with one host species, three gyrodactylids infected hosts within the same family, and one infected fishes from three different families. This study demonstrates that the northernmost lake in the Neotropics harbours a monogenean fauna of clear Neotropical affinity.