Operculomyces is a new genus in the order Rhizophydiales

In recent years molecular phylogenies based on analyses of rDNA sequences have advanced knowledge of the Chytridiomycota, but much alpha taxonomic work remains. We have discovered an operculate chytrid that molecular phylogenies placed in the Rhizophydiales, an order that currently contains a single operculate species, the rest having inoperculate zoospore release. Because descriptions of genera in the Chytridiomycota now rely on transmission electron microscopic features of the zoospore as well as molecular evidence we studied the zoospore ultrastructure of the isolate to confirm its placement in the Rhizophydiales and to evaluate it as a new genus. Its suite of ultrastructural characters confirmed its placement within the Rhizophydiales, and its J-shaped, multilayered spur and the position of the nonflagellate centriole at a slight angle to the kinetosome make it unique within the Rhizophydiales, thus supporting molecular evidence indicating that the isolate represents a new genus. Herein we describe zoospore ultrastructure and scanning electron and light microscopic level morphology of this monocentric, endogenous, operculate chytrid and describe it as a new genus and species, Operculomyces laminatus.