Non-conspecificity of Cylindrocladium quinqueseptatum and Calonectria quinqueseptata based on a β-tubulin gene phylogeny and morphology

Cylindrocladium quinqueseptatum Boedijn & Reitsma was originally described from leaf spots of Hibiscus sabdariffa L. from Indonesia. This fungus infects many host plants in Southeast Asia and causes severe leaf blight disease of eucalypts. Calonectria quinqueseptata Figueiredo & Namek., which was described from leaf spots on Annona squamosa L. from Brazil, has been regarded as the teleomorph of Cy. quinqueseptatum. Based on morphology and on the phylogeny derived from the DNA sequence of a beta-tubulin gene portion spanning several phylogenetically informative introns, the two respective ex-type cultures are shown to be distinct species. Furthermore, Calonectria reteaudii (Bugn.) C. Booth (anamorph Cy. reteaudii (Bugn.) Boesew.), which was described on Smithia bequaertii De Wild. from Vietnam, is shown to be morphologically identical to a comprehensive selection of isolates of Cy. quinqueseptatum from Southeast Asia, Australia, and Madagascar. As Cy. reteaudii represents an older name for Cy. quinqueseptatum, we suggest that the fungus causing widespread damage on eucalypts and other hosts in the above regions be referred to as Cy. reteaudii. Calonectria quinqueseptata should be retained for the fungus that thus far has been found only in Brazil.