title: Actinosporean stages of myxozoan parasites of oligochaetes from Lake Sasajewun, Algonquin Park, Ontario: new forms of triactinomyxon and raabeia.
abstract: Eight forms of triactinomyxon and 6 forms of raabeia of oligochaetes from Lake Sasajewun, Algonquin Park are described. Of the 8 forms of triactinomyxon, 2 designated as triactinomyxon 'B' and 'E' were found in both Limnodrilus hoffmeisteri and Tubifex tubifex. Three additional forms, designated as triactinomyxon 'A,' 'C,' and 'D,' occurred in L. hoffmeisteri. One form infecting L. hoffmeisteri was identified as Triactinomyxon ignotum Stolc, 1899, and another infecting T. tubifex was tentatively identified as Triactinomyxon dubium Granata, 1924. One form infecting L. hoffmeisteri and Rhyacodrilus coccineus was designated as triactinomyxon 'F.' Of the 6 forms of raabeia, 4 designated as raabeia 'A,' 'B,' 'C,' and 'F' were found in L. hoffmeisteri, and 2 designated as raabeia 'D' and 'E' were recorded in T. tubifex. The sporoplasmic mass of each form of triactinomyxon usually moved posteriorly within the cavity of the spore axis and was released through its posterior end, whereas the sporoplasmic mass of each form of raabeia was released through the anterior end of the epispore. An increase in the number of germ cells was observed in the floating spore stage of triactinomyxon 'B,' 'D,' 'E,' and raabeia 'B.'
authors.affiliation: Department of Zoology, University of Toronto, Ontario, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Xiao
authors.forename: S S
authors.initials: SS
authors.lastname: Desser
mesh_terms: D000818:Animals; D056890:Eukaryota / Q000145:classification* / Q000254:growth & development / Q000648:ultrastructure; D005618:Fresh Water; D009835:Oligochaeta / Q000469:parasitology*; D009864:Ontario