Lobulomycetales, a new order in the Chytridiomycota

The Chytridiales, one of the four orders in the Chytridiomycetes (Chytridiomycota), is polyphyletic, but contains several well-supported clades. One of these clades is referred to as the Chytriomyces angularis clade, and the phylogenetic placement of this group within the Chytridiomycetes is uncertain. The morphology and zoospore ultrastructure of C. angularis have been studied using LM and were shown to differ from those of the type species of Chytriomyces, which is in the Chytridiaceae and is phylogenetically distinct from the C. angularis clade. In this study, chytrids with morphologies or rDNA sequences similar to C. angularis, including two isolates of the morphologically similar C. poculatus, were isolated and their phylogenetic relationships determined using molecular sequence data. Results of Bayesian and MP analyses of nuSSU and partial nuLSU rDNA sequences grouped the new isolates and the type isolate of C. angularis in a monophyletic clade within the Chytridiomycota but distinct from the Chytridiaceae. Zoospores of isolates examined using TEM had ultrastructural features similar to those of C. angularis. Genetic analyses, ultrastructural data, and morphology support the establishment of a new order Lobulomycetales, placement of C. angularis and C. poculatus in a new genus (Lobulomyces), and description of additional taxa, which we have named Clydaea vesicula and Maunachytrium keaense.