Systematics and diversity of the Phyllachoraceae associated with Rosaceae, with a monograph of Polystigma

Abstract

Biotrophic members of the Phyllachoraceae are described and illustrated, and their nomenclature assessed. Isothea is considered to be a monotypic genus with close affinities to Phyllachora . Four species of Phyllachora are accepted; some have distinctive features which may provide evidence for subdivision of that genus. Two species currently referred to Plectosphaera are studied; neither is a typical biotroph. Polystigma is formally monographed. Five species are accepted, all on species of Prunus , including the previously undescribed P. amygdalinum , an economically important pathogen of almond (Prunus dulcis) . An eastern Russian species originally described in Polystigmella is treated as a subspecies of the widespread plum pathogen Polystigma rubrum . A number of species names is excluded from the Phyllachoraceae.