A new species of parasitic nematode, Hysterothylacium spirale sp. nov. (Ascaridoidea, Anisakidae), is described based on specimens collected from the intestine and pyloric caeca of the silvery john dory Zenopsis conchifer (Lowe) (Zeiformes, Zeidae), from the Argentinean Shelf (35°05′–40°46′S, 53°03′–58°07′W). Among the 66 valid species described so far in the genus, the new species most closely resembles H. zenis (Baylis, 1929). Both species, apparently specific for fishes of the family Zeidae, share the shape of the dorsal lip, the long expanded lateral alae originating from subventral interlabia and the ornamentation of the tail tip, as well as general morphometry. The combination of these shared features distinguishes both species from all congeners so far known. However, the new species is distinguishable from H. zenis by having shorter interlabia, and consequently the lateral alae originating more posteriorly, shorter spicules, a smaller number of postcloacal papillae and the presence of two pairs of double postcloacal papillae.
 Baylis H.A. 1929. Parasitic Nematoda and Acanthocephala collected in 1925–1927. Discovery Report, 1, 541–560. Search in Google Scholar
 Bruce N.L. 1990. Hysterothylacium Ward and Magath, 1917, and Ichthyascaris Wu, 1949, ascaridoid nematodes from Australian demersal fishes. Memoirs of Queensland Museum, 28, 389–426. Search in Google Scholar
 Bruce N.L., Adlard R.D., Cannon L.R.G. 1994. Synoptic checklist of ascaridoid parasites (Nematoda) from fish hosts. Invertebrate Taxonomy, 8, 583–674. DOI: 10.1071/IT9940583. http://dx.doi.org/10.1071/IT994058310.1071/IT9940583Search in Google Scholar
 Bush A.O., Lafferty K.D., Lotz J.M., Shostak A.W. 1997. Parasitology meets ecology on its own terms: Margolis et al. revisited. Journal of Parasitology, 83, 575–583. DOI: 10.2307/3284227. http://dx.doi.org/10.2307/328422710.2307/3284227Search in Google Scholar
 Deardorff T.L., Overstreet R.M. 1980. Review of Hysterothylacium, and Iheringascaris (both previously = Thynascaris) (Nematoda: Ascaridoidea) from the Northern Gulf of Mexico. Proceedings of the Biological Society of Washington, 93, 1035–1079. Search in Google Scholar
 Li L., An R., Zhang L. 2007. A new species of Hysterothylacium (Nematoda: Anisakidae) from marine fishes from Yellow Sea, China, with a key to the species of the genus Hysterothylacium. Zootaxa, 1614, 43–52. Search in Google Scholar
 Li L., Xu Z., Zhang L. 2008. Redescription of three species of Hysterothylacium (Nematoda: Anisakidae) from marine fishes from the Yellow Sea, China, with the synonymy of Hysterothylacium muraenesoxin (Luo, 1999). Zootaxa, 1878, 55–67. Search in Google Scholar
 Navone G.T., Sardella N.H., Timi J.T. 1998. Larvae and adults of Hysterothylacium aduncum (Rudolphi, 1802) (Nematoda: Anisakidae) in fishes and crustaceans in the South West Atlantic. Parasite, 5, 127–136. Search in Google Scholar
 Raffel T.R., Anderson T.K. 2009. A new species of Hysterothylacium (Nematoda: Anisakidae) from the stomach of the red-spotted newt, Notophthalmus viridescens, from Pennsylvania fishless ponds. Journal of Parasitology, 95, 1503–1506. DOI: 10.1645/GE-2092.1. http://dx.doi.org/10.1645/GE-2092.110.1645/GE-2092.1Search in Google Scholar PubMed
 Timi J.T. 2007. Parasites as biological tags for stock discrimination in marine fish from South American Atlantic waters. Journal of Helminthology, 81, 107–111. DOI: 10.1017/S0022149X07726561. http://dx.doi.org/10.1017/S0022149X0772656110.1017/S0022149X07726561Search in Google Scholar PubMed
 Yamaguti S. 1941. Studies on the helminth fauna of Japan. Part 33. Nematodes of fishes II. Japanese Journal of Zoology, 9, 343–408. Search in Google Scholar
© 2011 W. Stefański Institute of Parasitology, PAS
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.