Molecular phylogeny of the genera Andracantha, Bolbosoma and Corynosoma (Polymorphidae): challenging the current classification

HERNÁNDEZ-ORTS, JESUS S.; GARCÍA-VARELA, M.; SCHOLZ, TOMAS; MARTINEK, I. N. ; GARCIA, N; LOIZAGA, ROCIO; LANDETE, D. N. ; LISITSYNA, O. I. ; KUZMINA, T. A. ; AZNAR, F. J.

Dijon

Workshop; 10th Acanthocephalan Workshop; 2022

Species of the genus Corynosoma infect pinnipeds as definitive hosts, but adults of few species havealso been described from cetaceans, sea birds, sea otters and in an Australian rodent. In contrast, speciesof Bolbosoma mature exclusively in cetaceans, whereas Andracantha species use piscivorous birds asdefinitive hosts. Early multi-gene molecular phylogenetic analyses have placed these three genera in awell-supported clade sister to other polymorphid genera. These phylogenies supported the monophylyof Andracantha while the monophyletic origins of Bolbosoma and particularly Corynosoma remaincontroversial. Here, we present the most comprehensive phylogenetic analysis of Andracantha,Bolbosoma and Corynosoma using a three gene dataset (small and large nuclear ribosomal RNAsubunits and cytochrome c oxidase subunit I). The dataset included 15 of the 29 nominal species ofCorynosoma as well as five of the twelve and four of the nine species of Bolbosoma and Andracantha,respectively. More than 70 high-quality sequences were generated from morphologically verified andvouchered specimens. Maximum likelihood and Bayesian inference analyses revealed Andracantha asparaphyletic. Furthermore, Corynosoma appeared as non-monophyletic although with low support. Theresulting phylogram did not resolve the relationships between the genera Andracantha, Bolbosoma andCorynosoma and more representatives are required to increase the accuracy of their phylogeneticrelationships. However, the results of our analyses challenge the current morphological classification ofAndracantha and a new diagnosis of this genus is required. Andracantha sigma from fish-eating birdsof New Zealand should be transferred to Corynosoma, as this species appears in a strongly supportedassociation with some Antarctic species of Corynosoma from penguins and seals. Finally,morphological and molecular data suggest the possible finding of a cryptic species complex withinCorynosoma parasitising penguins.