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Centraalbureau voor Schimmelcultures, Fungal Biodiversity Centre (CBS), Utrecht, The Netherlands
M.M. Geldenhuis
M.J. Wingfield
Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa
M.H. Schoeman
Institute for Tropical and Subtropical Crops, Nelspruit, South Africa
Y.-F. Yen
W.-C. Shen
Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, Taiwan
B.D. Wingfield
Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa
Psidium guajava wilt is known from South Africa, Malaysia and Taiwan. The fungus causing this disease, Myxosporium psidii, forms dry chains of conidia on surfaces of pseudoparenchymatous sporodochia, which develop in blisters on bark. Similar sporodochia are characteristic of Nalanthamala madreeya, the type species of Nalanthamala. Nalanthamala, therefore, is the appropriate anamorph genus for Myxosporium psidii, while Myxosporium is a nomen nudum (based on M. croceum). For M. psidii the combination Nalanthamala psidii is proposed. Nalanthamala psidii, the palm pathogen Gliocladium (Penicillium) vermoesenii, another undescribed anamorphic species from palm, two species of Rubrinectria and the persimmon pathogen Acremonium diospyri are monophyletic and belong to the Nectriaceae (Hypocreales) based on partial nuclear large subunit ribosomal DNA (LSU rDNA) analyses. Rubrinectria, therefore, is the teleomorph of Nalanthamala, in which the anamorphs are classified as N. vermoesenii, N. diospyri or Nalanthamala sp. Nalanthamala squamicola, the only other Nalanthamala species, has affinities with the Bionectriaceae and is excluded from this group. Rubrinectria/Nalanthamala species form dimorphic conidiophores and conidia in culture. Fusiform, cylindrical, or allantoid conidia arise in colorless liquid heads on acremonium-like conidiophores; ovoidal conidia with somewhat truncated ends arise in long, persistent, dry chains on penicillate conidiophores. No penicillate but irregularly branched conidiophores were observed in N. diospyri. Conidia of N. psidii that are held in chains are shorter than those of N. madreeya, of which no living material is available. Nalanthamala psidii and N. diospyri are pathogenic specifically to their hosts. They form pale yellow to pale orange or brownish orange colonies, respectively, and more or less white conidial masses. Most strains of Rubrinectria sp., Nalanthamala sp. and N. vermoesenii originate from palm hosts, form mostly greenish or olive-brown colonies and white-to-salmon conidial masses. They form a mono-phyletic clade to which Nalanthamala psidii and N. diospyri are related based on analyses of the internal transcribed spacer regions and 5.8S rDNA (ITS rDNA), LSU rDNA, and partial ß-tubulin gene. Few polymorphic sites in the ITS rDNA and ß-tubulin gene indicate that Nalanthamala psidii comprises two lineages, one of which has been detected only in South Africa.
Key words: ß-tubulin gene, internal transcribed spacer, Nalanthamala madreeya, Nalanthamala squamicola, Nectriaceae, nuclear large subunit ribosomal DNA, phylogeny, systematics, wilt disease
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