Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2012
Publication Date: 12/5/2012
Citation: Salgado-Salazar, C., Rossman, A.Y., Samuels, G.J., Capdet, M., Chaverri, P. 2012. Multigene phylogenetic analyses of the Thelonectria coronata and T. veuillotiana species complexes. Mycologia. 104(6):1325-1350. Interpretive Summary: Each year fungi cause billions of dollars damage to crop and forest plants. One group of fungi causes canker diseases of hardwood trees including beech bark canker as well as root and rhizome rots. Two common tropical species in this group of fungi were discovered to be species complexes. The relationships among the species in this complex have been delimited based on a number of new collections. In this paper nine new species are described and illustrated as well as the two previously known species. All species in this group were characterized using molecular sequences as well as morphological features. A key to the eleven species is provided. This research will be used by plant diagnosticians and forest pathologists who need to identify these fungi.
Technical Abstract: Thelonectria is a recently established genus of common and ubiquitous saprophytic fungi on woody hosts, previously placed in the genus Neonectria. Thelonectria coronata and T. veuillotiana occur sympatrically in several geographical areas in tropical, subtropical, and temperate regions. Recent studies in fungal systematics have demonstrated that within species significant diversity can be masked by phenotypic similarity. Previous taxonomic studies including T. coronata and T. veuillotiana suggested these fungi could represent cryptic species complexes; however, the morphological characters exhibit few differences useful for resolving species limits. In order to assess the status of T. coronata and T. veuillotiana, a phylogenetic analysis of six genomic regions was combined with a morphological examination of specimens. Based on the multigene phylogeny reconstructed using Maximum Parsimony, Maximum Likelihood, and Bayesian approaches, five phylogenetic groups in T. coronata and six in T. veuillotiana could be identified. As is common for cryptic species, clear and unequivocal diagnostic morphological characters could not be identified; however, average values of morphological traits tend to be different among the phylogenetic groups. An increased level of non-synonymous/synonymous substitutions in ß-tubulin gene and a decreased or absent production of conidia was detected within the T. coronata complex, possibly indicating the homothallic nature of these isolates. Here, T. coronata and T. veuillotiana and related species are described and illustrated; a dichotomous key to all species is provided.