Systematics of Conidiobolus (Entomophthorales) using numerical taxonomy. I. Biology and cluster analysis

Abstract

The morphology and taxonomic history of the genus is reviewed. In field studies, substrates yielding isolates of Conidiobolus were varied, and success in obtaining isolates appeared to be correlated with high moisture. Conidiobolus coronatus was very abundant. Isolates of this fungus varied greatly in abundance of villose resting spores and 14 did not produce microconidia. Ranges in diameters of microconidia and primary conidia were greater than previously described. Thick walls developed in conidia from the field isolates projected onto Petri-dish lids. This phenomenon could be a means for surviving unfavorable conditions. Morphological examinations were performed on 17 type specimens of Conidiobolus species, and on cultures representing 36 of the named taxa after obtaining single-spore isolates. The ability to produce various spore types was readily lost in culture. The primary conidia of all type cultures were determined to be multinucleate. Optical density at 725 nm and dry weight of known packed cell concentrations were measured and found to have a linear relationship. Utilization of five nitrogen sources and four carbon sources was determined for the type cultures by using optical density. Cluster analysis of the named taxa was done using NTSYS, based on morphological and nutritional characters.