Morphology and zoospore discharge in single-pored, epibiotic Chytridiales

Abstract

Five eucarpic, epibiotic chytrids with single discharge pores were examined in culture, and morphological variation on different substrates was reported. Species studied include Rhizophydium constantineani Saccardo; Rhizophydium sphaerocarpum (Zopf) Fischer var. sphaerocarpum; Rhizoclosmatium globosum H. E. Petersen; Chytridium lagenaria Schenk, and Chytridium confervae (Wille) Minden. These chytrids could be classified according to four methods of zoospore discharge: (I) inoperculate and non-vesicular; (II) inoperculate and vesicular; (III) operculate and non-vesicular; and (IV) operculate and vesicular. Presence of a membraneless vesicle during discharge was shown to be of as much taxonomic significance as the presence of an operculum. Taxonomic criteria and phylogeny are discussed.