First integrative study of the diversity and specificity of metacercariae of Dubois, 1936 from native and introduced fishes in the Caribbean.

Metacercariae of the genus are often recorded in freshwater fish hosts. While the diversity and taxonomy of this genus are receiving increasing attention in molecular phylogenetic studies, available data remain geographically biased. Most molecular studies of and morphologically similar (neascus) worms originate in North America and Europe and Asia (more than 60% of DNA sequences are from USA and Canada), with few data currently available from the Neotropics, where high host diversity suggests high and under-sampled parasite diversity. In this study, we report molecular and morphological data from metacercariae of in fish in Puerto Rico, where only a single species has been previously reported. Partial sequences of cytochrome oxidase subunit 1 from metacercariae from (native to Puerto Rico) and the introduced fishes , , and revealed 7 genetically distinct species-level lineages, of which 4 were novel. We report novel molecular life-cycle linkages in (metacercariae in muscle of the cichlid ), a species previously known only from adults in birds from South America; and in sp. 23 (metacercariae in poeciliids), which has recently been found in in Georgia, USA. We also report the first molecular data from sp. 8 in in the Caribbean. Metacercariae of most species were morphologically distinguished and all displayed narrow specificity for fish hosts, with no indication of parasite sharing among introduced and native fishes.