Speciation and Synonymy in Penicillium Subgenus Penicillium — Towards a Definitive Taxonomy

Summary

Until a few years ago, taxonomy of asexual, haploid fungi such as Penicillium relied primarily on morphological or gross physiological characters. Although, in Penicillium, a large measure of agreement existed, in the final analysis speciation depended on the concepts of the individual taxonomist. The resulting lack of agreement was nowhere more obvious than in Penicillium subgenus Penicillium. Recent developments have changed all this. In particular, the introduction of simple techniques for studying secondary metabolites and improved methods for distinguishing isoenzymes by gel electrophoresis have resulted in independent methods for assessing species concepts.

Backed by accurate identifications using traditional methods, careful studies using secondary metabolite profiles and isoenzyme patterns have produced remarkably consistent results both within and between species. Correlations are so clear that it can now be stated confidently that we are approaching a definitive taxonomy for subgenus Penicillium.

Of course some new species can be expected to be discovered as unfamiliar habitats are explored, for example, new species and varieties described from seed stores of marsupials on the U.S. prairies. Leaving these latter aside because their status has not yet been fully assessed, some 25 well defined species can be distinguished in subgenus Penicillium.

This paper sets out species in subgenus Penicillium as currently conceived by the authors. For each species a diagnosis is given, and a list of synonyms where these have been confirmed by studies on living cultures. Notes on species concepts, ecology and mycotoxin production are also given.