Zoospore ultrastructure of three Chytridium species and Rhizoclosmatium globosum

Abstract

Zoospore cytology of Chytridium lagenaria Schenk, C. confervae (Wille) Minden, C. olla Braun, and Rhizoclosmatium globosum H. E. Petersen is described. Zoospores of C. confervae, C. olla, and R. globosum have many ultrastructural characteristics in common and, considered of particular significance, show similarities in the basal area by the kinetosome; here two sets of three electron-dense, stacked, plate-like bodies are on the side of the kinetosome opposite to a parallel, non-functional centriole. Zoospores of C. lagenaria instead of having plate-like bodies have an electron-dense, half-saddle-shape structure partially covering the kinetosome. The position of certain organelles in C. lagenaria further distinguishes it from the other three species. Zoospores of all four species have a membrane-bound cluster of ribosomes, usually a single lipid body with a rumposome and microbody in association with it, a bundle of microtubules which connect the rumposome and kinetosome, and, in the peripheral area, a striated (paracrystalline) inclusion. Comparison with other chytrids is made and taxonomic implications are discussed.