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Abstract
Phylogenies inferred from the analysis of DNA sequence data have shown that the Onygenales contains clades that do not correspond with previously described families. One lineage identified in recent molecular phylogenetic studies includes the dimorphic pathogens belonging to the genera Ajellomyces, Emmonsia and Paracoccidioides. To evaluate the degree of support for this lineage and determine whether it includes additional taxa, we examined relationships among the members of this clade and selected saprobic onygenalean taxa based on maximum-parsimony analyses of partial nuclear large RNA subunit (LSU) and internal transcribed spacer (ITS) sequences. A clade distinct from the Onygenaceae was found to encompass Ajellomyces (including the anamorph genera Blastomyces, Emmonsia and Histoplasma) and Paracoccidioides brasiliensis. The members of this lineage are saprobic and pathogenic vertebrate-associated taxa distinguished by their globose ascomata with coiled appendages, muricate globose or oblate ascospores, and lack of keratinolytic activity. Anamorphs are solitary aleurioconidia or irregular alternate arthroconidia. Based on molecular data and on morphological and physiological similarities among these taxa, we propose the new family, Ajellomycetaceae.
We are indebted to Gary McNeely (Brandon University) for his suggestions for the improvement of this manuscript and to Michael H. Hertwig-Jaksch for assistance with the Latin diagnosis. Financing for this study was provided to the senior author in the form of an A.W. Mellon Postdoctoral Fellowship in Plant Systematics (Duke University, USA). Operating grants from the Natural Sciences and Engineering Research Council (NSERC) of Canada to Wendy Untereiner and to Lynne Sigler and a NSERC undergraduate research summer assistantship to Jason Bachewich are gratefully acknowledged.