Phylogenetic and taxonomic evaluation of Chalara, Chalaropsis, and Thielaviopsis anamorphs associated with Ceratocystis

Abstract

Parsimony analysis of sequences of the internal transcribed spacer region of the nuclear rDNA and partial sequences of the large subunit (LSU) place four anamorphic Chalara species as a monophyletic grouping within the teleomorph genus Ceratocystis. Chalara ovoidea, Ch. thielavioides, Ch. populi, and Ch. elegans (synanamorph: Thielaviopsis basicola) form aleurioconidia typical of the anamorph genus Thielaviopsis, to which the species are transferred. Three of these species (T. ovoidea, T. thielavioides, and T. populi) are morphologically similar to each other but are shown to be distinct by rDNA sequences. The anamorphic genera Chalaropsis and Hughesiella are considered synonyms of Thielaviopsis. Thielaviopsis punctulata, which forms aleurioconidia singly, is shown to be the anamorph of Ce. radicicola. The respective anamorphs for Ce. coerulescens, Ce. fagacearum, and Ce. eucalypti, which lack aleurioconidia, are also transferred to the amended genus Thielaviopsis as T. ungeri, T. quercina, and T. eucalypti. Although Ch. australis and Ch. neocaledoniae do not form aleurioconidia, they are placed in Thielaviopsis based on their endoconidial state and clear affinities to Ceratocystis eucalypti. Three apparently asexual Ambrosiella species belong in the Ce. moniliformis clade based on LSU rDNA sequences, but the cultures available are not suitable for detailed morphological study, and these species are not transferred to Thielaviopsis.

• Ascomycetes
• Ceratocystis paradoxa
• rDNA
• Thielaviopsis paradoxa

The authors are indebted to Walter Gams and the Centraalbureau voor Schimmelcultures (Baarn, Netherlands) for providing strains and Meredith Blackwell (Louisiana State University, USA) for providing Ambrosiella isolates. Thanks go to Keith Seifert and Scott Mahady for their helpful comments on the manuscript. This research was supported by the National Science Foundation through the grant DEB-9870675. Journal Paper No. J-19131 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project No. 3226, and supported by Hatch Act and State of Iowa funds.