Morphological and molecular characterisation of a new genus and species of acanthocephalan, Tenuisoma tarapungi n. g., n. sp. (Acanthocephala: Polymorphidae) infecting red-billed gulls in New Zealand, with a key to the genera of the Polymorphidae Meyer, 1931


Acanthocephalans of the family Polymorphidae Meyer, 1931 are cosmopolitan parasites that infect the intestines of fish-eating birds and mammals. Polymorphid acanthocephalans recovered from the intestines of red-billed gulls (Chroicocephalus scopulinus (Forster)) from the Otago coast, New Zealand, although morphologically similar to the genus Arhythmorhynchus Lühe, 1911 nevertheless have a unique molecular profile showing considerable genetic differentation, and are here diagnosed and described as Tenuisoma tarapungi n. g., n. sp. Characters which distinguish T. tarapungi include a very elongate, cylindrical hindtrunk, swollen anterior trunk with a spinose region, a secondary swelling in males only containing the testes, and hypodermal nuclei distributed throughout the length of the trunk. Molecular data (cox1, 18S, 28S) confirm that the representative of the new genus is closest to, but nonetheless strongly divergent from species of Pseudocorynosoma Aznar, Pérez-Ponce de León & Raga, 2006. Immature specimens are described and illustrated, demonstrating the extreme degree of hindtrunk inversion occurring in immature individuals of this species. We provide a key to the genera of the family Polymorphidae.

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The authors would like to thank the Dunedin Wildlife Hospital for their kind donation of bird specimens, Phil McKenna for supplying the North Island specimens, and Robert Poulin for his support. This work has been supported indirectly by the Marsden Fund (Royal Society of New Zealand) and a Zoology Department PBRF Research Enhancement grant to Professor Robert Poulin.

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Presswell, B., Bennett, J.D.L. & Smales, L.R. Morphological and molecular characterisation of a new genus and species of acanthocephalan, Tenuisoma tarapungi n. g., n. sp. (Acanthocephala: Polymorphidae) infecting red-billed gulls in New Zealand, with a key to the genera of the Polymorphidae Meyer, 1931. Syst Parasitol 97, 25–39 (2020).

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