Species of Mycosphaerella and Their Anamorphs Associated with Leaf Blotch Disease of Eucalyptus in South Africa

Abstract

Mycosphaerella leaf blotch is a serious disease of Eucalyptus nitens and also occurs on several other Eucalyptus spp. in South Africa. The aim of the present study was to characterize the variation observed among South African Mycosphaerella strains obtained from eucalypts. Earlier studies had suggested that only one species, M. molleriana, occurred on eucalypts in South Africa. Contrary to these reports M. molleriana was not found, but five new species of Mycosphaerella were collected and are described here. The name M. juvenis is proposed for the species commonly associated with leaf spots on juvenile leaves of E. nitens. Because its cercosporoid anamorph state could not be suitably accommodated in Pseudocercospora, a new genus Uwebraunia is introduced for it, and also for the anamorphs of two other new species, M. ellipsoidea and M. lateralis, occurring on E. cladocalyx and E. grandis x saligna, respectively. Mycosphaerella crystallina with a Pseudocercospora anamorph is described as a new species from leaves of E. bicostata. A Pseudocercospora sp. associated with spermogonia of an undescribed Mycosphaerella sp., is compared with known species of the genus from eucalypts, and described as P. epispermogoniana. Mycosphaerella marksii, recently described from eucalypts in Australia, is also reported from South Africa for the first time. A key to the species of Mycosphaerella presently known from Eucalyptus is also provided.