Increasing taxonomic representation of rhinebothriids to improve their phylogenetic analysis and its morphological circumscription

Abstract

In recent years, the class Cestoda has undergone considerable taxonomic changes, mainly on the supra-generic categories. This restructuring was mostly due to the contribution of new insights into the phylogenetic relationships of taxa based on molecular data. However, numerous taxa still need to be revised; for instance: the family Rhinebothriidae Euzet, 1953. This family includes 71 species of endoparasites of batoids, organized in 8 genera distributed worldwide. Recent phylogenetic hypotheses indicate that the systematics of the group is inadequate, specially because its type-genus, Rhinebothrium Linton, 1890 is polyphyletic. The full understanding of the diversity of rhinebothriids is crucial to elucidate the composition of the family, to circumscribe its type-genus and, to test the taxonomic status of other genera. The present ambiguity of the internal sister-group relationships among members of this family is attributed to low taxonomic and molecular data representation. Within this framework, the adoption of modern approaches to obtain new molecular markers in conjunction with the extension of their taxonomic representation is the logical strategy to resolve the systematics of the group. Here, we propose to conduct a phylogenetic study on the phylogeny of Rhinebothriidae using mitogenomic and nuclear ribosomal genes for a unprecedented taxonomic and biogeographical representation to: (i) provide an unambiguous circunscription of Rhinebothrium; (ii) describe new species for the genus with the inclusion of representatives from the Brazilian coast; (iii) test the taxonomic status of the genera which recent phylogenetic hypotheses undermine the monophyly of Rhinebothrium; and (iv) propose a robust phylogenetic hypothesis for sister-group relationships among members of Rhinebothriidae.