DAO 66:227-232 (2005)  -  doi:10.3354/dao066227

Taxonomy and molecular phylogeny of Myxobolus bilobus n. sp. (Myxozoa) parasitizing Notemigonus crysoleucas (Cyprinidae) in Algonquin Park, Ontario, Canada

David K. Cone1,*, Jing Yang1, Genlou Sun1, Russell Easy2

1Department of Biology, Saint Mary’s University, Robie Street, Halifax, Nova Scotia B3H 3C3, Canada
2National Research Council, Institute for Marine Biosciences, Oxford Street, Halifax, Nova Scotia B3H 3Z1, Canada

ABSTRACT: Myxobolus bilobus n. sp. (Myxozoa) is described from golden shiner Notemigonus crysoleucas in Algonquin Park, Ontario, Canada. Plasmodia develop at the distal end of gill filaments, where they form a novel-shaped plasmodium made up of 2 side-by-side hemispheres joined at a central pore. Surrounding gill tissue is vacuolated, necrotic, and hemorrhagic. Spores of M. bilobus n. sp. resemble those of M. aureatus Ward, 1919, M. angustus Kudo, 1934, M. spalli Landsberg & Lom, 1991, and M. pseudokoi Li & Desser, 1985 in parasitizing cyprinids and in their pyriform shape. Spores of M. bilobus n. sp., however, are much larger (20 to 22.1 µm long, 7.5 to 9.3 µm wide, and 6 µm thick) than those of these other species, and the plasmodium is bi-lobed rather than the typical hollow sphere. A phylogenetic analysis of the 18S rDNA (2014 bp) reveals that M. bilobus n. sp. is a member of a clade that includes 11 species of Myxobolus, all of which are parasites of cyprinid fishes in North America or Eurasia. The study concludes that M. bilobus n. sp. is a member of a clade that has undergone radiation within cyprinid fishes of the 2 continents and that this evolution has involved both host and site switching.


KEY WORDS: Myxozoan · Myxobolus bilobus n. sp. · Notemigonus crysoleucas


Full text in pdf format