On the Taxonomy of Mrazekidae: Resurrection of the Genus Bacillidium Janda, 192812

ABSTRACT. This paper reviews the taxonomy of the microsporidia of the family Mrazekidae Léger & Hesse, 1922, based on reexamination of slides in the collection of Prof. O. Jirovec, Prague, and discusses the available type material of Mrazekia argoisi and Bacillidium criodrili. Mrazekia argoisi differs prominently from the other species, and the genus Mrazekia is restricted to this species. The aberrant cytology and development exclude the species from the phylum Microspora. The genus Bacillidium is resurrected for the type species B. criodrili and for four other species. The genus Jirovecia is retained, and five species are transferred to this genus. A new family is erected for Bacillidium and Jirovecia. As B. criodrili does not exhibit octosporoblastic, pansporoblastic sporogony, the recent taxonomic treatment of the genus Bacillidium by Issi is rejected. Mrazekia jiroveci Sprague, 1977, the new name for B. limnodrili Jirovec, 1936, is rejected.