Diplodia quercivora sp. nov.: a new species of Diplodia found on declining Quercus canariensis trees in Tunisia

Abstract

During a study of the species of Botryosphaeriaceae associated with oak decline in Tunisia, a large collection of Diplodia strains were isolated from Quercus afares, Q. canariensis and Q. suber trees showing a progressive dieback of shoots and branches, trunk canker and exudates and collar rot. Most of the isolates were identified as Diplodia corticola, while two isolates from Q. canariensis were morphologically and phylogenetically (ITS and tef1-α sequences data) distinct from all other known species of Diplodia. They are described here as Diplodia quercivora sp. nov. In addition, phylogenetic analyses showed for the first time the existence of two distinct lineages within D. corticola. In artificial inoculation experiments, D. quercivora caused necrotic lesions on bark and wood of three Mediterranean oak species, Q. ilex, Q. pubescens and Q. suber. In particular, among the oak species tested, Q. pubescens was the most susceptible.

• Botryosphaeriaceae
• Diplodia
• oak decline
• phylogeny
• taxonomy

Acknowledgments

The authors thank Antonio Deidda and Bruno Scanu (University of Sassari, Italy), Foued Hasnaoui (Institut Sylvo–Pastoral de Tabarka, Tunisia), Clizia Sechi and Salvatore Seddaiu (Dipartimento della ricerca per il sughero e la silvicoltura, Agris Sardegna, Italy) for assistance during pathogenicity tests and field sampling. Artur Alves was supported by the program Ciência2008, co-financed by the Human Potential Operational Program (National Strategic Reference Framework 2007–2013) and European Social Fund (EU).

Part of this work was supported by Fundação para a Ciência e a Tecnologia (Portugal) through grant PEst-OE/BIA/UI0457/2011. Alan Phillips acknowledges support by the Regione Autonoma della Sardegna, visiting professor program at the University of Sassari, Italy.