Circumscription of Botryosphaeria species associated with Proteaceae based on morphology and DNA sequence data

Botryosphaeria spp. occur on and cause diseases of Proteaceae, but accurate identification has been problematic due to the lack of clear species circumscriptions of members of this genus. In this study, 46 isolates of Botryosphaeria from proteaceous hosts growing in various parts of the world were studied, using morphology, cultural characters and sequence data from the ITS region of the rDNA operon. Five Botryosphaeria spp. were found to be associated with Proteaceae. Botryosphaeria lutea was isolated from Banksia and Buckinghamia spp. in Australia, and a single isolate was obtained from Protea cynaroides in South Africa. Botryosphaeria proteae was associated only with South African Proteaceae, but occurred in many parts of the world. Another Botryosphaeria sp. that occurred exclusively on South African Proteaceae represents a new taxon that is described as B. protearum. This pathogen was found on South African Proteaceae cultivated in Australia; Hawaii; Portugal, including the Madeira Islands; and South Africa. Botryosphaeria ribis was associated with both South African and Australian Proteaceae and was isolated from material collected in Australia, Hawaii and Zimbabwe. A single occurrence of B. obtusa as an endophyte was recorded from P. magnifica in South Africa. In addition to providing a taxonomic overview of Botryosphaeria spp. associated with Proteaceae, this paper clarifies for the first time the global distribution of these species. A key also is provided to facilitate their identification. A large number of new host and distribution records are made and a new species of Botryosphaeria from Proteaceae is described.