Eighty-four isolates of Penicillium chrysogenum and related
species
were examined by isozyme analysis. Four main groups could be
defined by cluster analysis; P. chrysogenum var. chrysogenum,
P. flavigenum sp. nov., P. chrysogenum var. dipodomyis
and P. nalgiovense.
P. flavigenum is described as new species, and P.
chrysogenum var. dipodomyis raised to species level as P.
dipodomyis. The genetic
distance between these groups was calculated by employing a formula that
accounts for the differences in alleles and loci obtained
by isozyme analysis of these fungi. The genetic distances and cluster
analysis suggest that the groups should be considered as four
separate species. The practical implication of the separation and the
ecological characteristics of the four species are discussed.