Blood flukes (Digenea: Aporocotylidae) of marine fishes from off northern Patagonia, Argentina, with the redescription of Aporocotyle argentinensis Smith, 1969

Aporocotyle is the second richest genus of fish blood flukes within the family Aporocotylidae. These cosmopolitan trematodes infect the heart, bulbus arteriosus, and blood vessels of marine fishes belonging to the orders Gadiformes, Ophidiiformes, Perciformes, Pleuronectiformes, and Scorpaeniformes. In this study, three species of Aporocotyle, i.e. A. argentinensis, A. mariachristinae, and A. ymakara, from teleost fishes collected in the San Matías Gulf, Patagonia, Argentina, are morphologically and genetically characterized. Re-examination of these blood flukes provided new detailed drawings, measurements, photomicrographs, confocal and scanning electron microscopy (SEM) images. Aporocotyle argentinensis is redescribed based on type-, voucher- and newly collected material from the bulbus arteriosus, heart and gill blood vessels of the Argentine hake Merluccius hubbsi from Argentina. We generated partial sequences for the large subunit of the nuclear ribosomal RNA (28S rRNA) and the mitochondrial cytochrome c oxidase subunit 1 (cox1) genes for A. argentinensis and A. ymakara and used these sequences to investigate the phylogenetic relationships of these blood flukes. Our morphological analyses highlighted the taxonomic importance of the distribution of tegumental spines, the extension of the posterior caeca, and the presence of a genital atrium to circumscribe and classify species of Aporocotyle. Phylogenetic analyses recovered A. mariachristinae and A. ymakara as closely related taxa and placed the new sequences of A. argentinensis in a clade together with previously published sequences of isolates identified as A. argentinensis from three hake species (Merluccius hubbsi, M. gayi and M. australis) from Argentina, Chile, Peru and the Falkland Islands. This study provides a comprehensive review of the diversity of Aporocotyle in the southwest Atlantic, contributing to a better understanding of the systematics and evolutionary history of these blood flukes.

Universitat de València
Natural History Museum of Geneva
Consejo Nacional de Investigaciones Científicas y Técnicas
Natural History Museum London
Universidad Nacional Autónoma de México
Czech Academy of Sciences, Biology Centre