Species ofGyrodactylusvon Nordmann, 1832 (Monogenea Gyrodactylidae) from poeciliid fishes, with a description ofG. turnbullisp. nov. from the guppy,Poecilia reticulataPeters

Gyrodactylus bullatarudis Turnbull, 1956 is described from Xiphophorus helleri × X. maculatus hybrids. Specimens from this host were morphologically indistinguishable from material of this species from Poecilia reticulata and P. sphenops, although differences in host specificity were noted. Gyrodactylus turnbulli sp. nov., a member of the G. eucaliae species group, is described from Poecilia reticulata. Gyrodactylus turnbulli has frequently been confused with G. bullatarudis, although the two species are only distantly related. They can be distinguished by differences in the structure of the dorsal bar, which is deeply notched in G. bullatarudis, and by the relative length of the ventral bar processes.