Boothiomyces Angulosus And Boothiomyces Elyensis: Two New Combinations In The Terramycetaceae (Rhizophydiales, Chytridiomycota)

The genus Rhizophydium was proposed by A. Schenk in 1858 to accommodate the inoperculate taxa previously placed in Chytridium. The morphological delineation encompassed around 235 species that have now been segregated into different genera based on molecular and zoospore ultrastructural analyses. However, some taxa have never been investigated for phylogenetic position or zoospore ultrastructural characters. The aim of this study was to use morphology, zoospore ultrastructure and molecular analyses to verify the placement of our isolates of Rhizophydium angulosum and R. elyense in the Rhizophydiales phylogeny. These isolates produced angular zoosporangia, characteristic of Terramycetaceae representatives, and grouped within the Boothiomyces Glade in analyses of complete ITS and partial LSU regions of rDNA. Transmission electronic microscopy (TEM) analysis revealed that R. angulosum produces zoospores with the same ultrastructural characters described from Boothiomyces representatives. In addition, R. elyense presented sufficient characteristics that support its morphological delineation from Boothiomyces macroporosus, the type species of the genus. Based on molecular, morphological, and ultrastructural analyses, we transfer R. angulosum and R. elyense to Boothiomyces.