Microidium phyllanthi-reticulati sp nov on Phyllanthus reticulatus

A new powdery mildew species of the genus Microidium (Erysiphaceae) found on Phyllanthus reticulatus (Phyllanthaceae) in Thailand is described. Microidium phyllanthireticulati [= Oidium phyllanthi var. reticulati] is characterized by having amphigenous colonies on the host surface, long conidiophore foot-cells twisted at the base, and barrel-shaped to cylindrical conidia with Microidium-type germ tubes. The new species differs from the allied and morphologically very similar M. phyllanthi in producing smaller conidia and conidiophores with longer foot-cells. Analyses of rDNA ITS + 28S sequence data support the separation of M. phyllanthi-reticulati from M. phyllanthi. The new species is described and illustrated in detail, and compared with other species assigned to Microidium.