Phylogenetic reassessment of the coelomycete genus Harknessia and its teleomorph Wuestneia (Diaporthales), and the introduction of Apoharknessia gen. nov.

During routine surveys for microfungi from the Fynbos of the Cape Floral Kingdom in South Africa, isolates of several Harknessia species were collected. Additional isolates of Harknessia spp. were collected from Eucalyptus leaves in South Africa, as well as elsewhere in the world where this crop is grown. Interspecific relationships of Harknessia species were inferred based on partial sequence of the internal transcribed spacer (ITS) nuclear ribosomal DNA (nrDNA), as well as the beta-tubulin and calmodulin genes. From these data, three new species are described, namely H. globispora from Eucalyptus, H. protearum from Leucadendron and Leucospermum, and H. capensis from Brabejum stellatifolium and Eucalyptus sp. Furthermore, based on large subunit nrDNA sequence data, Harknessia is shown to be heterogeneous, and a new genus, Apoharknessia, is introduced for A. insueta, which is distinguished from H. eucalypti, the type species of Harknessia, by having an apical conidial appendage. A morphologically similar genus, Dwiroopa, which is characterized by several prominent germ slits along the sides of its conidia, is shown to cluster basal to Harknessia. Species of Harknessia, and their teleomorphs accommodated in Wuestneia, are shown to represent an undescribed family in the Diaporthales, as is Apoharknessia, for which no teleomorph is known.