Reconsidering species boundaries in the Ceratocystis paradoxa complex, including a new species from oil palm and cacao in Cameroon

Abstract

The Ceratocystis paradoxa complex accommodates a group of fungal pathogens that have become specialized to infect mostly monocotyledonous plants. Four species currently are recognized in this group, including C. paradoxa, which has a widespread distribution and broad host range. In this study, multigene phylogenetic analyses involving sequences of the ITS, β-tubulin and TEF-1α gene loci, in combination with phenotypic and mating studies, were used to characterize purported C. paradoxa isolates from Cameroon and to compare them with isolates from elsewhere, including protologs and type specimens of known species. We show that the C. paradoxa complex comprises substantially greater species diversity than previously recognized. One new species in this group is described from Cameroon as Ceratocystis cerberus, while C. paradoxa sensu stricto (s. str.) and four other species are redefined. Lectotypes are designated for C. ethacetica and Endoconidium fragrans (synonym of C. ethacetica), while epitypes are designated for C. paradoxa s. str., C. ethacetica and C. musarum. A neotype is designated for Catenularia echinata (synonym of C. ethacetica) and two species, previously treated in Thielaviopsis, are transferred to Ceratocystis.

• Ceratocystidaceae
• Microascales
• phylogenetic species concept
• Thielaviopsis

Acknowledgments

We thank Walter Gams, David Hawksworth and John McNeill for advice and comments regarding various taxonomic issues treated in this study. Aimé D. Begoude Boyogueno and Alain C. Misse provided assistance during field studies for which we are most grateful. We acknowledge the financial assistance of the Department of Corporate International Affairs of the University of Pretoria, members of the Tree Protection Cooperative Programme (TPCP) and the Department of Science and Technology (DST)/National Research Foundation (NRF) Center of Excellence in Tree Health Biotechnology (CTHB). We recognize logistical support of the Institute of Agricultural Research for Development (IRAD) during field studies in Cameroon.