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Adult worms of the genus Floridosentis are endoparasites of marine fishes of the genus Mugil and are broadly distributed in the Americas. Currently, Floridosentis includes two species, F. mugilis, distributed in the Gulf of Mexico and along the Atlantic Ocean coast, and F. pacifica, restricted to the Pacific Ocean coast. The aim of this study was to explore the species limit of both species of the genus Floridosentis, collected in 37 localities in eight countries: Mexico, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, Ecuador and Venezuela. We sequenced 253 specimens to build a comprehensive dataset for three genes: the cytochrome c oxidase subunit I (cox 1) from mitochondrial DNA, the internal transcribed spacers ITS1 and ITS2 including the 5.8S gene (ITS region), and the D2 + D3 domains of the large subunit (LSU) of nuclear DNA. Maximum likelihood and Bayesian analyses with the cox 1 and concatenated (cox 1 + ITS+LSU) datasets were conducted. Two species delimitation methods were implemented, the Automatic Barcode Gap Discovery (ABGD), and Bayesian species delimitation (BPP), plus a haplotype network inferred with 253 specimens, allowing us to validate two nominal species of Floridosentis., F. mugilis, plus one linage distributed in the Gulf of Mexico and along the Atlantic Ocean coast, and F. pacifica, plus two additional lineages distributed along the Pacific Ocean coast. All these lineages are shared by both species of mullet (Mugil curema and M. cephalus). The currents in the Atlantic Ocean, Pacific Ocean and Gulf of Mexico, in combination with the biology of the definitive hosts, have played a key role in the distribution of the two nominal species and of the three lineages of Floridosentis across the Americas., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Species of the allocreadiid genus Creptotrema are parasites of freshwater fishes in the Americas. Species in the genus possess one pair of muscular oral lobes on the oral sucker. Currently, the genus contains eight species, six distributed in South America, one in Middle America and one in North America. Genetic data are only available for the North American species, Creptotrema funduli, a parasite of fundulids originally described from Oneida Lake, New York State. In this study, we obtained 28S ribosomal DNA sequences of trematodes morphologically similar to Creptotrema agonostomi from the mountain mullet, Dajaus monticola, across a wide geographical range in Middle America. Our molecular phylogenetic analyses showed that (1) the genus Creptotrema, as currently conceived, is not monophyletic; (2) the allocreadiids in mountain mullets should be re-allocated in the genus Pseudoparacreptotrema; and (3) the allocreadiid trematodes from D. monticola across Middle America represent four morphologically similar species, three of which can be distinguished genetically. These three new species are described herein using an integrative taxonomy approach. We contend that accurate estimates of species diversity and phylogenetic relationships among allocreadiids, and most likely other species of trematodes, necessarily require an integrative taxonomy approach that should consider at least DNA sequences and scanning electron microscopy.