Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Description of Uncinaria lyonsi n. sp. (Nematoda: Ancylostomatidae) from the California sea lion Zalophus californianus Lesson (Carnivora: Otariidae)


A new species of hookworm, Uncinaria lyonsi n. sp., is described based on morphological studies of the nematodes collected by Dr. E. T. Lyons from the California sea lion Zalophus californianus (Lesson) on San Miguel Island, California, USA. The new species is morphologically similar to three other species of the genus Uncinaria Frölich, 1789 parasitising pinnipeds, U. lucasi Stiles, 1901, U. hamiltoni Baylis, 1933 and U. sanguinis Marcus, Higgins, Šlapeta & Gray, 2014, in the body dimensions, the structure of the buccal capsule, the shape and structure of the male caudal bursa and female genital system. Uncinaria lyonsi n. sp. is differentiated from U. lucasi by having longer spicules and gubernaculum, larger buccal capsule and more slender oesophagus. The new species differs from U. hamiltoni and U. sanguinis in having shorter spicules and narrower buccal capsule. The latter two species also occur in the Southern Hemisphere and are geographically separated from U. lyonsi n. sp. The present study confirms the existence of a host-specific species of Uncinaria in the California sea lion, previously revealed by molecular and biological investigations.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3


  1. Baylis, H. A. (1933). A new species of the nematode genus Uncinaria from a sea lion with some observations on related species. Parasitology, 25, 308–316.

  2. Baylis, H. A. (1947). A redescription of Uncinaria lucasi Stiles. A hookworm of seals. Parasitology, 38, 160–162.

  3. Berón-Vera, B., Crespo, E. A., Raga, J. A., & Pedraza, S. N. (2004). Uncinaria hamiltoni (Nematoda: Ancylostomatidae) in South American Sea Lions, Otaria flavescens, from Northern Patagonia, Argentina. Journal of Parasitology, 90, 860–863.

  4. Castinel, A., Duignan, P. J., Pomroy, W. E., Lyons, E. T., Nadler, S. A., Dailey, M. D., Wilkinson, I. S., & Chilvers B. L. (2006). First report and characterization of adult Uncinaria spp. in New Zealand Sea Lion (Phocarctos hookeri) pups from the Auckland Islands. New Zealand. Parasitology Research, 98, 304–309.

  5. Dailey, M. D. (1975). The distribution and intraspecific variation of helminth parasites in pinnipeds. Rapport et Procès-Verbaux des Réunions-Conseil International pour l’Exploration de la Mer, 169, 338–352.

  6. Dailey, M. D., & Brownell, R. L. Jr. (1972). A checklist of marine mammal parasites. In: Ridgway, S. H. & Charles, C. T. (Eds) Mammals of the Sea. Springfield: Biology and Medicine, pp. 528–589.

  7. Dailey, M. D., & Hill, B. L. (1970). A survey of metazoan parasites infesting the California (Zalophus californianus) and Steller (Eumetopias jubatus) sea lion. Bulletin of the Southern California Academy of Sciences, 69, 126–132.

  8. King, J. E. (1983). Seals of the World, 2nd edn. Ithaca, N.Y.: British Museum (Natural History). & Cornell Unversity Press, 240 pp.

  9. Lichtenfels, J. R. (1980). Keys to genera of the superfamilies Ancylostomatoidea and Diaphanocephaloidea. In: Anderson, R. C., Chabaud, A. G. & Willmott, S. (Eds) CIH Keys to the Nematode Parasites of Vertebrates, No. 8. Farnham Royal, Bucks, UK: Commonwealth Agricultural Bureaux, 26 pp.

  10. Lyons, E. T., & DeLong, R. L. (2005). Photomicrographic images of some features of Uncinaria spp. (Nematoda: Ancylostomatidae) from otariid pinnipeds. Parasitology Research, 95, 346–352.

  11. Lyons, E. T., DeLong, R. L., Gulland, F. M., Melin, S. R., Tolliver, S. C., & Spraker, T. R. (2000). Comparative biology of Uncinaria spp. in the California sea lion (Zalophus californianus) and the northern fur seal (Callorhinus ursinus) in California. Journal of Parasitology, 86, 1348–1352.

  12. Lyons, E. T., DeLong, R. L., Melin, S. R., & Tolliver, S. C. (1997). Uncinariasis in northern fur seal and California sea lion pups from California. Journal of Wildlife Diseases, 33, 848–852.

  13. Lyons, E. T., DeLong, R. L., Spraker, T. R., Melin, S. R., Laake, J. L., & Tolliver, S. C. (2005). Seasonal prevalence and intensity of hookworms (Uncinaria spp.) in California sea lion (Zalophus californianus) pups born in 2002 on San Miguel Island. California. Parasitology Research, 96, 127–132.

  14. Lyons, E. T., Melin, S. R., DeLong, R. L., Orr, A. J., Gulland, F. M., & Tolliver, S. C. (2001). Current prevalence of adult Uncinaria spp. in northern fur seal (Callorhinus ursinus) and California sea lion (Zalophus californianus) pups on San Miguel Island, California, with notes on the biology of these hookworms. Veterinary Parasitology, 97, 309–318.

  15. Marcus, A. D., Higgins, D. P., Šlapeta, J., & Gray, R. (2014). Uncinaria sanguinis sp. n. (Nematoda: Ancylostomatidae) from the endangered Australian sea lion, Neophoca cinerea (Carnivora: Otariidae). Folia Parasitologica, 61, 255–265.

  16. Margolis, L., & Dailey, M. D. (1972). Revised annotated list of parasites from sea mammals caught off the west coast of North America. NOAA Technical Report, 647, 1–23.

  17. Nadler, S. A., Adams, B. J., Lyons, E. T., DeLong, R. L., & Melin, S. R. (2000). Molecular and morphometric evidence for separate species of Uncinaria (Nematoda: Ancylostomatidae) in California sea lions and northern fur seals: hypothesis testing supplants verification. Journal of Parasitology, 86, 1099–1106.

  18. Nadler, S. A., Lyons, E. T., Pagan, C., Hyman, D., Lewis, E. E., Beckmen, K., Bell, C. M., Castinel, A., DeLong, R. L., Duignan, P. J., Farinpour, C., Huntington, K. B., Kuiken, T., Morgades, D., Naem, S., Norman, R., Parker, C., Ramos, P., Spraker, T. R., & Berón-Vera, B. (2013). Molecular systematics of pinniped hookworms (Nematoda: Uncinaria): species delimitation, host associations and host-induced morphometric variation. International Journal for Parasitology, 43, 1119–1132.

  19. Ramos, P., Lynch, M., Hu, M., Arnould, J. P. Y., Norman, R., & Beveridge, I. (2013). Morphometric and molecular characterization of the species of Uncinaria Frölich, 1789 (Nematoda) parasitic in the Australian fur seal Arctocephalus pusillus doriferus (Schreber), with notes on hookworms in three other pinniped hosts. Systematic Parasitology, 85, 65–78.

  20. Soulsby, E. J. L. (1982). Helminths, arthropods and protozoa of domesticated animals, 7th edn. Philadelphia: Lea & Febiger, 809 pp.

  21. Wynen, L. P., Goldsworthy, S. D., Insley, S. J., Adams, M., Bickham, J. W., Francis, J., Gallo, J. P., Hoelzel, A. R., Majluf, P., White, R. W., & Slade, R. (2001). Phylogenetic relationships within the eared seals (Otariidae: Carnivora): implications for the historical biogeography of the family. Molecular Phylogenetics and Evolution, 21, 270–284.

  22. Yonezawa, T., Kohno, N., & Hasegawa, M. (2009). The monophyletic origin of sea lions and fur seals (Carnivora; Otariidae) in the Southern Hemisphere. Gene, 441, 89–99.

Download references


We would like to thank to Dr. Eugene T. Lyons from the University of Kentucky, Maxwell H. Gluck Equine Research Centre (Lexington, KY, USA), Dr. Steven Nadler from the University of California (Davis, CA, USA), and Dr. Eric Hoberg, curator of the U.S. National Parasite Collection (Beltsville, MD, USA), for the specimens of Uncinaria kindly loaned for our study. The morphological studies of the nematodes were performed using the equipment of the Centre of Collective Equipment Usage “Animalia”, NAS of Ukraine (Kyiv, Ukraine).

Author information

Correspondence to Tetiana A. Kuzmina.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kuzmina, T.A., Kuzmin, Y. Description of Uncinaria lyonsi n. sp. (Nematoda: Ancylostomatidae) from the California sea lion Zalophus californianus Lesson (Carnivora: Otariidae). Syst Parasitol 90, 165–176 (2015). https://doi.org/10.1007/s11230-014-9539-7

Download citation


  • Excretory Pore
  • Buccal Capsule
  • United States National Parasite Collection
  • Oesophagus Length
  • Posterior Bulb