Taxonomic Implications of Intraspecific Variation Amongst Isolates of the Aphid-Pathogenic Fungi Zoophthora radicans Brefeld and Z. phalloides Batko (Zygomycetes, Entomophthoraceae)

Abstract

Numbers of isolates, provisionally identified by classical morphological criteria as Zoophthora radicans or Z. phalloides, were compared over a range of morphological, physiological and biochemical attributes to .assess intraspecific and interspecific variation. Taxonometric analysis of results from 17 of the fungal isolates confirmed that these two species are distinct. The traditional criterion for separating these species, the morphology of the primary conidia, is shown to be satisfactory. In addition, biochemical tests proved useful. Fatty acid composition was suitable for making between-species distinctions and isoenzyme analysis showed up small variations within species. The Z. phalloides isolates could be further divided into two groups on the basis of their geographical origins, Europe or North America.

The European strain of Z. phalloides best fitted the original species description. It is judged that the North American strain, although distinct, is not sufficiently different to justify the erection of a new species.