DNA phylogeny reveals polyphyly of Phoma section Peyronellaea and multiple taxonomic novelties

Abstract

Species of the anamorph genus Phoma are commonly isolated from a wide range of ecological niches. They are notoriously difficult to identify due to the paucity of morphological features and the plasticity of these when cultivated on agar media. Species linked to Phoma section Peyronellaea are typified by the production of dictyochlamydospores and thus have additional characters to use in taxon delineation. However, the taxonomy of this section is still not fully understood. Furthermore the production of such chlamydospores also is known in some other sections of Phoma. DNA sequences were generated from three loci, namely ITS, actin, and β-tubulin, to clarify the phylogeny of Phoma taxa that produce dictyochlamydospores. Results were unable to support section Peyronellaea as a taxonomic entity. Dictyochlamydospore formation appears to be a feature that developed, or was lost, many times during the evolution of Phoma. Furthermore, based on the multigene analyses, five new Phoma species could be delineated while a further five required taxonomic revision to be consistent with the genetic variation observed.

• actin
• β-tubulin
• coelomycetes
• dictyochlamydospores
• ITS
• multigene phylogeny
• taxonomy

This research was supported by the Dutch Ministry of Agriculture, Nature and Food Quality through an endowment of the FES program “Versterking infrastructuur Plantgezondheid”. The authors are extremely grateful for the help of Mrs Karin Rosendahl (PD) and Dr Amy Rossman (Systematic Botany and Mycology Laboratory) who provided strains. We thank Mrs Marjan Vermaas for her help in preparing the photo plates and Dr Cécile Gueidan for her help with the phylogenetic analyses. We are further indebted to Prof Dr Pierre de Wit and Dr Chiel Noordeloos for their critical discussions on the manuscript.