Phylogeny in the genus Penicillium: a morphologist's perspective

Great advances have taken place in our understanding of the taxonomy of Penicillium and its teleomorphs in the past 15 years. Physiological and biochemical techniques, applied in conjunction with morphology, have enabled the taxonomy of this difficult genus to approach consensus. Such information, plus existing molecular data, have been used here to construct a hypothetical phylogeny. The proposed phylogeny is based on a number of postulates, including the following: (i) evolution has proceeded from holomorph to strict anamorph; (ii) an intermediate stage exists, the sclerotigenic anamorph; (iii) Eupenicillium and Talaromyces, the Penicillium holomorphs, are of separate (though related) origin; (iv) species in Penicillium have arisen on multiple occasions from these holomorphic genera; and (v) evolution among Penicillium species is away from floccose growth and sparsely produced penicilli, away from irregular penicilli, and away from the soil habitat. Physiologically, evolution is towards growth at low temperature and low water activity and towards mycotoxin production. These and other criteria have been used to construct a hypothetical phylogeny of the major species in Talaromyces, Eupenicillium, and Penicillium, which is offered as a framework for future molecular studies.