Morphological observations on three Baltic species of Corynosoma Lühe, 1905 (Acanthocephala, Polymorphidae)

Sonja Leidenberger, Sven Boström, Matthew T. Wayland


Necropsies of Baltic grey (Halichoerus grypus) and ringed seals (Pusa hispida) presented a rare opportunity to study their acanthocephalan fauna. Both species hosted adults of three species of the genus Corynosoma Lühe, 1904, namely C. magdaleni Montreuil, 1958, C. semerme (Forsell, 1904) Lühe 1911 and C. strumosum (Rudolphi, 1802) Lühe 1904. A comparative morphological analysis of these three species of Corynosoma, combining both light and scanning electron microscopy, was performed for the first time. Sexual dimorphism in the size and shape of the trunk was observed in both C. magdaleni and C. semerme, but there was insufficient material to investigate this phenomenon in C. strumosum. Genital spines were not observed in any of the female acanthocephalans. Three possible explanations for the presence of genital spines in some females, but not others are (i) cryptic speciation, (ii) phenotypic variation and (iii) loss by extraction or shearing when the copulatory cap is released. Copulatory caps were observed on female C. semerme. The size and morphology showed considerable variability and all caps were strongly autofluoresecent.


Baltic Sea; grey seals; ringed seals; sem; thorny-headed worms

Full Text:




Amin O.M., Heckmann R.A., Halajian A. & El-Naggar A.M. 2011. The morphology of an unique population of Corynosoma strumosum (Acanthocephala, Polymorphidae) from the Caspian seal, Pusa caspica, in the land-locked Caspian Sea using SEM, with special notes on histopathology. Acta Parasitologica 56: 438−445.

Arai H.P. 1989. Acanthocephala. In: L. Margolis & Z. Kabata (eds), Guide to the Parasites of Fishes of Canada. Part III: 1–41. Canadian Special Publication of Fisheries and Aquatic Sciences 107, Ottawa.

Aznar F.J., Bush A.O., Fernández M. & Raga J. A. 1999. Constructional morphology and mode of attach-ment of the trunk of Corynosoma cetaceum (Acanthocephala: Polymorphidae). Journal of Morphology 241: 237–49.<237::AID-JMOR6>3.0.CO;2-A

Aznar F.J., Pérez-Ponce de Léon G. & Raga J.A. 2006. Status of Corynosoma (Acanthochephala: Polymorphidae) based on anatomical, ecological, and phylogenetic evidence, with the erection of Pseudocorynosoma n. gen. Journal of Parasitology 92: 548−564.

Crompton D.W.T. 1985. Reproduction. In: Crompton D.W.T. & Nickol B.B. (eds) Biology of the Acanthocephala: 213−263. Cambridge University Press, Cambridge.

Dezfuli B.S., Onestini S., Carcupino M. & Mischiati C. 1998. The cement apparatus of larval and adult Pomphorhynchus laevis (Acanthocephala: Palaeacanthocephala). Parasitology 116: 437−447.

Dezfuli B.S., Capuano S., Pironi F. & Mischiati C. 1999. The origin and function of cement gland secretion in Pomphorhynchus laevis (Acanthocephala). Parasitology 119: 649−653.

Forssell A.L. 1904. Echinorhynchus semermis n. sp. Meddelanden af Societatis pro Fauna et Flora Fennica 13: 175−179.

Forssell A.L. 1905. [Contribution to the knowledge of echinorhynchs of fishes in Finland.] Acta Societatis pro Fauna et Flora Fennica 27: 1−29. [In Swedish.]

García-Varela M., Francisco J.A., Pérez-Ponce de León G., Piñero D. & Laclette J.P. 2005. Molecular phylogeny of Corynosoma Lühe, 1904 (Acanthocephala), based on 5.8S and internal transcribed spacer sequences. Journal of Parasitology 91: 345–52.

Helle E. & Valtonen E.T. 1981. Comparison between spring and autumn infection by Corynosoma (Acanthocephala) in the ringed seal Pusa hispida in the Bothnian Bay of the Baltic Sea. Parasitology 82: 287−296.

Hernández-Orts J.S., Timi J.T., Raga J.A., García-Varela M., Crespo E.A. Aznar F.J. 2012. Patterns of trunk spine growth in two congeneric species of Acanthocephalan: investment in attachment may differ between sexes and species. Parasitology 139: 945–5.

Hernández-Orts J.S., Smales L.R., Pinacho-Pinacho C.D., García-Varela M. & Presswell B. 2017. Novel morphological and molecular data for Corynosoma hannae Zdzitowiecki, 1984 (Acanthocephala: Polymorphidae) from teleosts, fish-eating birds and pinnipeds from New Zealand. Parasitology International 66: 905−916.

Hewer H.R. 1964. The determination of age, sexual maturity, longevity and a life-table in the grey seal (Halichoerus grypus). Proceedings of the Zoological Society of London 142: 593-624.

Kaimoto T., Hirazawa T., Masubuchi T., Morohoshi A., Katahira H. & Kobayashi M. 2018. Host characteristics and infection level of an intestinal parasite Corynosoma strumosum (Acanthocephala) in the Kuril harbour seals of Erimo Cape, Hokkaido, Japan. Parasitology International 67: 237−244.

Leidenberger S. & Bäcklin B.-M. 2008. [Species determination and distribution of parasites of grey seals (Halichoerus grypus) with intestinal ulcers in Sweden]. NRM Rapport 2008-12-18. [In Swedish.] World Wide Web electronic publication. Available from [accessed Oct. 2018].

Leidenberger S. & Boström S. 2008. Characterization of the heartworm Acanthocheilonema spirocauda (Leidy, 1858) Anderson, 1992 (Nematoda: Onchocercidae) in Scandinavia. Parasitology Research 104: 63−67.

Leidenberger S. & Boström S. 2009. Description of the lungworm Otostrongylus circumlitus (Railliet, 1899) de Bruyn, 1933 (Metastrongyloidea: Crenosomatidae) found in the heart of seals from Sweden. Journal of Nematode Morphology and Systematics 12: 169−175.

Leidenberger S., Hårding K. & Härkönen T. 2007. Phocid seals, seal lice and heartworms: a terrestrial host-parasite system conveyed to the marine environment. Diseases of Aquatic Organisms 77: 235−253.

Lisitsyna O.I., Kudlai O., Spraker T.R., Tkach V.V., Smales L.R. & Kuzmina T.A. 2019. Morphological and molecular evidence for synonymy of Corynosoma obtuscens Lincicome, 1943 with Corynosoma australe Johnston, 1937 (Acanthocephala: Polymorphidae). Systematic Parasitology 96: 95-110.

Lühe M. 1904. Geschichte und Ergebnisse der Echinorhynchen-Forschung bis auf Westrumb (1821). (Mit Bemerkungen über alte und neue Gattungen der Acanthocephalen). Zoologische Annalen, Zeitschrift für Geschichte der Zoologie 1: 139−354.

Lühe M. 1911. Acantocephalen. Register der Acanthocephalen und parasitischen Plattwürmer, geordnet nach ihren Wirten. In: Brauer (ed.) Die Süsswasserfauna Deutschlands. Eine Exkursionsfauna. Heft 16: 35−41. Gustav Fischer Verlag, Jena.

Montreuil P.L. 1958. Corynosoma magdaleni sp. nov. (Acanthocephala), a parasite of the gray seal in Eastern Canada. Canadian Journal of Zoology 36: 205−215.

Mutterer J. & Zinck E. 2013. Quick-and-clean article figures with FigureJ. Journal of Microscopy 252: 89−91.

Nickol B.B., Helle E. & Valtonen E.T. 2002. Coryonosoma magdaleni in gray seals from the Gulf of Bothnia, with emended descriptions of Corynosoma strumosom and Corynosoma magdaleni. Journal of Parasitology 88: 1222−1229.[1222:CMIGSF]2.0.CO;2

Popov V.N. & Fortunato M.E. 1987. [Geographic variation of Corynosoma strumosum (Acanthocephala, Polymorphidae) – a parasite of marine mammals.] Zoologicheskii zhurnal 66 (1): 12–18. [In Russian.][Canadian Translation of Fisheries and Aquatic Science No. 5589. ISSN 0704-3726].

Rudolphi K.A. 1802. Fortsetzung der Beobachtungen über die Eingeweidewürmer. Archiv für Zoologie et Zootomie 2: 1−67.

Schindelin J., Arganda-Carreras I., Frise E., Kaynig V., Longair M., Pietzsch T., Preibisch S., Rueden C., Saalfeld S., Schmid B., Tinevez J.Y., White D.J., Hartenstein V., Eliceiri K., Tomancak P. & Cardona A. 2012. Fiji - an Open Source platform for biological-image analysis. Nature Methods 9: 676−682.

Schindelin J., Rueden C.T., Hiner M.C. & Eliceiri K.W. 2015. The ImageJ ecosystem: an open platform for biomedical image analysis. Molecular Reproduction and Development 82: 518−529.

Seinhorst J.W. 1959. A rapid method for the transfer of nematodes form fixative to anhydrous glycerine. Nematologica 4: 67−69.

Sinisalo T., Kunnasranta M. & Valtonen E.T. 2003. Intestinal helminths of a landlocked ringed seal (Phoca hispida saimensis) population in eastern Finland. Parasitology Research 91: 40−45.

Sinisalo T., Poulin R., Högmander H., Juuti T. & Valtonen E.T. 2004. The impact of sexual selection on Corynosoma magdaleni (Acanthocephala) infrapopulations in Saimaa ringed seals (Phoca hispida saimensis). Parasitology 128: 179−185.

Steinauer M.L., Nickol B.B. & Ortí G. 2007. Cryptic speciation and patterns of phenotypic variation of a highly variable acanthocephalan parasite. Molecular Ecology 16: 4097–4109.

Väinölä R., Valtonen E.T. & Gibson D.I. 1994. Molecular systematics in the acanthocephalan genus Echinorhynchus (senus lato) in northern Europe. Parasitology 108: 105−114.

Valtonen E.T., Helle E. & Poulin R. 2004. Stability of Corynosoma populations with fluctuating population densities of the seal definitive host. Parasitology 129: 635−642.

Van Cleave H.J. 1945. The genital vestibule and its significance in the morphology and taxonomy of the Acanthocephala, with particular reference to the genus Corynosoma. Journal of Morphology 77: 299–315.

Van Cleave H.J. 1953. Acanthocephala of North American Mammals. Illinois Biological Monographs 23. The University of Illinois Press, Urbana.

Waindok P., Lehnert K., Siebert U., Pawliczka I. & Strube C. 2018. Prevalence and molecular characterisation of Acanthocephala in pinnpedia of the North and Baltic Seas. International Journal of Parasitology: Parasites and Wildlife 7: 34−43.

Wayland M.T. 2010. Proboscis profiler: a tool for detecting acanthocephalan morphotypes. Systematic Parasitology 76: 159−167.


  • There are currently no refbacks.

License URL: