Passalora perplexa, an important pleoanamorphic leaf blight pathogen of Acacia crassicarpa in Australia and Indonesia

Passalora perplexa is described from lesions on blighted phyllodes of Acacia crassicarpa growing in northern Australia and Indonesia. The fungus develops two distinct conidiomatal synanamorphs from the same stroma in nature, one external and sporodochial (Type 1), the other internal and coelomycetous (Type 2). A third synanamorph (Type 3) develops as resting spores within cells of Type 2 conidia in culture. Type 1 conidiophores and conidia are consistent with Passalora sensu lato, with pigmented conidiophores and conidia and thickened, darkened, refractive scars. The conidiophores are initially caespitose and stromatal, but later sporodochial and generated by the outer cell layer of more or less protuberant stromata. Type 2 conidia are smaller, paler, cylindrical and mostly 1-septate. They have unthickened scars and are formed on short, 0-1-septate conidiophores which line a central cavity that develops within the same stroma. In culture, conidial cells of Type 2 conidia may eventually release an inner, hyaline propagule (Type 3 conidia) that possibly acts as a resting spore. The connection between Type 1 and Type 2 synanamorphs has been confirmed in culture via single-conidial isolates. Sequence data derived from the ribosomal DNA ITS region (ITS1, ITS2) and the 5.8S gene, show that P. perplexa is an anamorph of Mycosphaerella, closely allied with other species of Passalora. Passalora perplexa is a severe pathogen of Acacia crassicarpa in Indonesian plantations and has become a serious constraint to plantation development with this species.