The Botryosphaeriaceae represents an important and diverse family of latent fungal pathogens of woody plants. While some species appear to have wide host ranges, others are reported only from single hosts. It is, however, not clear whether apparently narrow host ranges reflect specificity or if this is an artifact of sampling. We address this question by sampling leaves and branches of native South African trees from four different families, including Acacia karroo (Fabaceae), Celtis africana (Cannabaceae), Searsia lancea (Anacardiaceae) and Gymnosporia buxifolia (Celastraceae). As part of this process, two new species of the Botryosphaeriaceae, namely Tiarosporella africana sp. nov. and Aplosporella javeedii sp. nov., emerged from sequence comparisons based on the ITS rDNA, TEF-1α, β-tubulin and LSU rDNA gene regions. An additional five known species were identified including Neofusicoccum parvum, N. kwambonambiense, Spencermartinsia viticola, Diplodia pseudoseriata and Botryosphaeria dothidea. Despite extensive sampling of the trees, some of these species were not isolated on many of the hosts as was expected. For example, B. dothidea, which is known to have a broad host range but was found only on A. karroo. This could have resulted from the fact that it is a rare species in the region. With the exception of S. lancea, which was infected by A. javeedii all the hosts were infected by more than one Botryosphaeriaceae species. Collectively, the results suggest that some intrinsic host factors, possibly combined with local environmental conditions, affect the distribution and co-infectivity of various hosts by the Botryosphaeriaceae.
2This would counteract the general ability of a species in the Botryosphaeriaceae to infect a broad range of plants. The combination of host and environmental factors might also explain why some Botryosphaeriaceae with apparently broad host ranges, are found on different suites of hosts in different areas of the world.