Calonectria eucalyptorum sp. nov., a new leaf blight pathogen of Eucalyptus from India.

In this study, Calonectria eucalyptorum sp. nov. is described from the blighted leaves of Eucalyptus in India using morphological and multi-locus phylogenetic analyses. The new species belongs to the Calonectria cylindrospora species complex, and its unique microscopic features and DNA sequence information enable clear separation from the 12 currently accepted species in this complex. Conidia of the new taxon are slightly longer than those of its phylogenetic neighbors. Additionally, this species produces central as well as lateral stipe extensions, which is a feature not known for the other members of the C. cylindrospora species complex. Analyses of the combined partial calmodulin, histone, translation elongation factor-1α, and β-tubulin gene regions revealed a distinct phylogenetic position for C. eucalyptorum. Recombination analysis provided additional support for the new species hypothesis. Koch's postulates for the new taxon as a foliar pathogen of Eucalyptus were fulfilled. The discovery of novel and pathogenic Calonectria species is important because it sheds light on species diversity, potential threats, and disease control.