Submitted to: Studies in Mycology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2010
Publication Date: 3/22/2011
Citation: Chaverri, P., Salgado, C., Hirooka, Y., Rossman, A.Y., Samuels, G.J. 2011. Delimitation of Neonectria and Cylindrocarpon (Nectriaceae, Hypocreales, Ascomycota) and related genera with Cylindrocarpon-like anamorphs. Studies in Mycology. 68:57-78. 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. The relationship among the species in this group of fungi is not well known. In this paper fungi of different species in this group were characterized using molecular sequences as well as morphological features. It was determined that these species represent four different groups or genera that differ biologically. The fungi that cause diseases on hardwood trees in temperate regions are very distinct from those in the tropics that live on dead woody tissues. These are different from the fungi that cause root and rhizome rots. Each group including three genera new to science is described and illustrated. A key to the four genera is provided. This research will be used by plant diagnosticians and forest pathologists who need to identify the fungi that cause these diseases.
Technical Abstract: Neonectria is a cosmopolitan genus and it is, in part, defined by its link to the anamorph genus Cylindrocarpon. Neonectria has been divided into informal groups on the basis of combined morphology of anamorph and teleomorph. Forty years ago Booth divided Cylindrocarpon into four groups defined by presence or absence of microconidia and chlamydospores. Molecular phylogenetic analyses have indicated that Neonectria s. str. and Cylindrocarpon s. str. are phylogenetically congeneric. In addition, morphological and molecular data accumulated over several years have indicated that Neonectria s. lat. and Cylindrocarpon s. lat. species do not form a monophyletic group and that the respective informal groups could represent distinct genera. In the present work we applied a multilocus analysis (act, ITS, LSU, rpb1, tef1, tub) to representatives of the informal groups in an effort to determine their level of phylogenetic support as a first step towards taxonomic revision of Neonectria s. lat. Results show five distinct highly supported clades that somewhat correspond with the informal Neonectria and Cylindrocarpon groups: (1) N. coccinea-group and Cylindrocarpon groups 1 & 4 (Neonectria/Cylindrocarpon s. str.); (2) N. rugulosa-group (Rugonectria gen. nov.); (3) N. mammoidea/N. veuillotiana-groups and Cylindrocarpon group 2 (Thelonectria gen. nov.); (4) N. radicicola-group and Cylindrocarpon group 3 (Ilyonectria gen. nov.); and (5) the anamorph genus Campylocarpon. Characteristics of the anamorphs and teleomorphs correlate with the five newly recognized genera. New combinations are made for species where their classification is confirmed by phylogenetic data.