ABSTRACTThe taxonomy ofPirellais examined. The genus is restricted to those mucoralean taxa producing deliquescent-walled sporangia on the apex of the main sporophore or its branches and persistent-walled sporangiola on short, twisted and contorted lateral branches arising either from the main sporophore or its branches, or directly from the substrate.Circinella naumoviiis transformed toPirella, asP. naumovii. Pirellacontains two taxa,P. circinansandP. naumovii.A key to species is provided.